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Quick Facts » Water Terms

Water is basic to our lives and all of us are affected by how it is used and managed. The complexity of our water laws and our water management structure is often bewildering. This fact sheet offers non-technical definitions of many of the commonly used water terms to help citizens better understand the principles that govern the use of water.


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Water Terms » Submersible Pumps Water Terminology


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Term Definition
[ A ]
AAU Amateur Athletic Union – A National organization with a division devoted to the athletic aspects of swimming.
ABRASION HAZARD A sharp or rough surface that would scrape the skin upon chance or by normal use modes.
ABSOLUTE FILTER RATING Filter rating meaning that 99.9 percent of essentially all of the particles larger than a specified micron rating will be trapped on or within the filter.
ABSORPTION The process of substance actually penetrating into the structure of another substance. This is different from adsorption in which one substance adheres to the surface of another.
ACCELERATION The rate at which velocity changes.
ACCESSIBLE Easily exposed for inspection and the replacement of materials and/or parts with the use of tools.
ACIDIC The condition of water or soil, which contains a sufficient amount of acid substances to lower the pH below 7.0.
ACTIVATED CARBON A form of elemental carbon whose particles have large surface area with adsorptive qualities, primarily used to remove chlorine, objectionable tastes and odors and numerous toxic organic compounds from water. Produced by heating carbonaceous substances, bituminous coal or cellulose-based substances such as wood or coconut shell, to 700 degrees Centigrade or less in the absence of air to form a carbonized char and then activating or oxidizing at 800 to 1000 degrees Centigrade with oxidizing gases such as carbon dioxide or steam to form pores, thus creating a highly porous adsorbent material.
ACTIVATED CARBON BLOCK A blend of fine activated carbon, water and a suitable binders(such as polyethylene or similar material) that is mixed and molded and hardened or extruded to a cartridge filter of any size and shape. Occasionally specialized media are added along with activated carbon to provide customized performances of specific contaminants such as lead.
ADSORPTION Attachment of a substance to a solid (or liquid) surface by non-specific means(as with carbon filtration techniques)
AERATION The process of adding air to a water supply for the purpose of oxidation(of materials such as iron, manganese, etc.)
AIR INDUCTION SYSTEM A system whereby a volume of air (only) is induced into hollow ducting built into a spa floor, bench or other location. The air induction system is activated by a separate air power unit (blower).
AIR PUMP ASSIST BACKWASH The compressing of a volume of air in the filter effluent chamber (by means of an air compressor or by the water pressure from the recirculating pump) which, when released, rapidly decompresses and forces water in the filter chamber through the elements in reverse, dislodging the filter aid and accumulated dirt, carrying it to waste.
AIR VOLUME CONTROL A device that maintains the air charge in a standard water storage tank. Pre-charged tanks do not require an air volume control.
ALGAE Green, black or brown microscopic plant life which is nourished by sunlight. A group of single-celled plants, which includes both seawater and fresh water varieties.
ALGICIDE A chemical or process for killing algae. An algistat is an agent for preventing their growth.
ALKALINITY A measurement of the quantity of chemicals present in water, which can neutralize acids. These include carbon dioxide, bicarbonate, carbonate and hydroxides. pH conditions which exceed 7.0.
ALUM A flocculating agent. Potassium and ammonium alum are the most common types used in the treatment of pool water. Aluminum sulphate is often used with gravity sand filters.
ALUMINUM SULFATE An aluminum salt commonly used as a flocculent by municipal water treatment facilities.
AMPHOTERIC A substance, such as aluminum, capable of acting as either an acid or base.
AMPS An electrical measurement of motor performance where current(amps) = voltage(volts)/resistance(ohms). Amps measures the flow of electricity.
ANAEROBIC A condition in which there is no air or no available free oxygen. Sometimes relates to microbes, which can exist without oxygen.
ANIONS See ion.
ANSI American National Standards Institute
AQUIFER Any geological formation containing water; one that supplies water for wells, springs, etc.
AREA The space on a flat plane bordered by two lines that can be measured in two directions (Length x Width = Area).
ASME American Society of Mechanical Engineers
ATMOSPHERIC PRESSURE The weight of the atmosphere at a given point on earth.
[ B ]
BACKWASH The process of flow reversal to clean a filter and to restore it to the normal clean condition for filtering with a minimum resistance to flow through the media.
BACKWASH CYCLE The operating time, after the filter cycle, required to completely clean the filter.
BACKWASH PIPING The pipe extended from the backwash outlet of the filters to a terminus at the point of disposal.
BACKWASH RATE The rate of application of water through a filter during the cleaning cycle expressed in gallons per minute per square foot of effective area.
BACTERIA Any of a class of microscopic plants having round, rod-like spiral or filamentous single cell or non-cellular bodies, often aggregated into colonies or mobile by means of flagella. Living in soil, water, organic matter or the bodies of plants and animals and being autotrophic (self-generative), saprophytic (digests chemicals already in their environment) or parasitic.
BACTERICIDE Material capable of inhibiting or destroying bacteria. Function is known as bactericidal.
BACTERIOSTATIC Material capable of reducing the rate of bacterial growth. Sometimes confused with bactericidal.
BATHER Any person using a pool, spa or hot tub and adjoining deck area for the purpose of water sports, recreation or related activities.
BEGINNERS AREA Those water areas in pools, spas and hot tubs which are three feet (3) or less in water depth.
BILL OF MATERIALS (BM) List of parts that are assembled into a pump at the factory
BINDERS When used in reference to cartridge filters, refers to chemicals used to hold, or bind, short fibers together in a filter. Also may refer to various chemicals used to bind polymeric compounds in products such as plastic bottles.
BIOFILM An aggregation of active, multi-layered microbes found on surfaces and in particular inside tubing and pipes. May be difficult to remove by chemical means due to multiple layers and lack of fluid dynamics at surfaces where it resides.
BLINDING The fouling or plugging of pores in a membrane, usually by a gel-like substance.
BOD Biochemical oxygen demand.
BODY FEED The continuous addition of small amounts of filter aid during the operation of a diatomaceous earth filter.
BOOSTER PUMP A pump that adds pressure to existing pressure in a water system.
BOOSTER PUMP SYSTEM A system whereby one or more hydrojets are activated by the use of a pump which is completely independent of the filtration and heating system of a spa. In other uses it is generally a pump and pressure tank controlled by a pressure switch or other device.
BRACKISH WATER Water containing between 1000 and 15000 mg/l of dissolved solids is generally considered to be brackish.
BRIDGING (OR SALT BRIDGING) The caking of salts in a dry water softener tank which causes failure of the liquid or brine beneath the dry salt to become saturated. The net result of bridging is insufficient salt to properly regenerate the resin.
BRINE (Same as Reject Water): One of two streams of fluids generated by a Distiller or Reverse Osmosis unit. It contains the impurities removed from the feed water. Characteristically, 30,000 to 300,000 ppm.
BROMIDE A compound of bromine. Two of the salts, Sodium and Potassium Bromide, are sometimes used to produce a disinfectant or algaecide.
BROMINE An element which is sometimes used in pool water purification. A dark, heavy, reddish-brown liquid in its normal state. Closely related to chlorine.
[ C ]
CAPACITY The amount of water a pump will put out or a tank will hold.
CARCINOGEN Any substance, which tends to produce cancer in an organism.
CARTRIDGE A replaceable porous filtering element.
CARTRIDGE - DEPTH TYPE A filter cartridge with a medium not less than three-fourths inch (3/4”) thick that relies on penetration of particulates into the medium to achieve their removal.
CARTRIDGE - SURFACE TYPE A filter cartridge with a medium less than three-fourths inch (3/4”) thick that relies on the retention of particulates on the surface of the cartridge to achieve their removal.
CATIONS See ion.
CAVITATION A condition that occurs in pumps when the water/liquid entering the pump is changed from a liquid state to a gaseous state and back to liquid that is generally caused by too high of flow rate or from pipe that is too small for the flow rate. The formation of vapor bubbles in areas of low pressure in a liquid.
CAVITATION DAMAGE The pitting or wearing away of a solid surface caused by the collapse of vapor bubbles created by low pressure prior to the damage.
CELLULASE An enzyme, which causes the decomposition of cellulose.
CELLULOSE ACETATE A synthetic polymer derived from naturally occurring cellulose and widely used in the fabrication of membranes. The polymers used for reverse osmosis membranes may be diacetate, triacetate or blends of these materials.
CENTRIFUGAL FORCE A force that tends to move something from the center to the outside of a rotating body.
CENTRIFUGAL PUMP A type of kinetic energy pump using centrifugal force(slinging motion) to accomplish it's work. A pump containing a rotation impeller or rotating vanes mounted on a shaft in a casing and turned by a power source. The rotating impeller uses centrifugal force to deliver water in a steady stream.
CENTRIFUGE A mechanical device that uses centrifugal or rotational forces to separate solids from liquids.
CHANNELING The greater flow of liquid through passages of lower resistance which can occur in fixed beds or columns of particles (carbon, etc.) due to non-uniform packing, irregular sizes and shapes of the particles, gas pockets, wall effects and other causes.
CHECK VALVE device that keeps water/liquid flowing one way through a pump or piping system
CHEMICAL FEEDER Any device to feed chemicals, but usually one feeding alum, acid, filter aid, algaecide, or soda ash. Included in this category are proportioning pumps, injector type feeders, pot type feeders, operating from a pressure differential, and dry type feeders.
CHLORAMINES Chemical complexes formed from the reaction between ammonia and chlorine. They are presently being used to disinfect municipal water supplies because unlike chlorine, they don't combine with organics in the water to form potentially dangerous carcinogens such as trihalomethanes (THM). Retains its bactericidal qualities for a longer time than free chlorine does. Chloramines can exist in three forms, the proportions of which depend on the physical and chemical properties of the water: Monochloramine; Dichloramine; Nitrogen Trichloride. Water containing chloramines must not be used for fish or kidney dialysis applications.
CHLORINATED HYDROCARBONS A group of organic chemicals formed by reacting petroleum-derived chemicals with chlorine. Such chemicals include pesticides (insecticides) and herbicides and are frequently potent carcinogens.
CHLORINATOR A device to feed, regulate the flow, and measure the amount of chlorine gas introduced into the water being treated.
CHLORINE An element, normally a gas, which is liquefied under pressure and stored in steel cylinders. Used as a disinfectant and algaecide when it is introduced in water solution into a pool or spa. A very toxic biocide. A halogen element isolated as a heavy irritating greenish-yellow gas of pungent odor, used as a bleach, oxidizing agent, and a disinfectant in water purification.
COAGULANT A chemical which causes dispersed colloidal particles to become destabilized, thereby aiding in their removal during municipal water treatment. Aluminum and iron salts are commonly used for this purpose.
COAGULATION A practice common in municipal water treatment in which a chemical (coagulant), most commonly alum, is added to water in order to destabilize colloidal particles by neutralization of their electrical charges. Coagulation is used, together with flocculation, as a process for colloid removal.
COD Chemical oxygen demand
COLLOIDAL MINERAL/COLLOID Un-dissolved, sub micron-sized, suspended particles which are well dispersed in a solution and will not readily settle out on standing. Most colloidal minerals are held in suspension by their tiny size and/or a static electrical charge. Many colloidal minerals claim to be organic due to the fact that they come from prehistoric mineral deposits such as humic shale and that some of the minerals are bound to carbon.
COMPACTION The undesirable physical compression of a reverse osmosis or ultrafiltration membrane which results in reduced flux rates. The phenomenon is accelerated at higher temperatures and pressures.
CONCENTRATE The portion of a feed stream that retains the ions, organics and suspended particles that were rejected during the cross flow filtration or purification process. Associated with water cooled distillers and reverse osmosis systems.
CONCENTRIC The shape of a pipe or fitting meaning perfectly round.
CONDENSATE Water obtained through distillation by evaporation and subsequent condensation.
CONDUCTIVITY A measure of the ability of an aqueous substance to transmit an electric current. The conductivity imparted to water by dissolved solids is a function of both the amount and composition of the salts and the temperature of the water.
CORROSION The etching or oxidation of a material by chemical action.
CORROSION RESISTANT MATERIAL A material with exceptional resistance to the corrosion factors to which it is subjected.
CROSS CONNECTION An unprotected connection between a domestic water system and any pool or other non-potable water whereby back flow to the domestic system could occur. Appropriate protection may be vacuum breakers, air gaps or other methods.
CYANURIC ACID A chemical used for chlorine stabilization.
[ D ]
D.E. Diatomaceous Earth, a type of filtration media. Can also stand for Dual Element when talking about electrical fusing.
DEAD HEAD Operating point on the curve where unit is pumping zero GPM - also known as Shut-off Head.
DECKS Those areas surrounding a pool, spa or hot tub that are specifically constructed or installed for use by bathers.
DEEP AREAS Portions of a pool, spa or hot tub having water depths in excess of five feet (5’).
DEIONIZATION Removal of ions from water by exchange with other ions associated with fixed charges on a resin. First, positively charged ions are removed, by a cation exchange resin, in exchange for a chemically equivalent amount of hydrogen ions. Second, negatively charged ions are removed, by an anion exchange resin for a chemically equivalent amount of hydroxide ions. The hydrogen and hydroxide ions introduced in this process unite to form water molecules. This process is also called demineralization by ion exchange.
DEMINERALIZATION The process of removing minerals from water e.g. deionization, reverse osmosis and distillation.
DESALINATION The removal of dissolved inorganic solids(salts) from a solution such as water to produce a liquid which is free of dissolved salts. Desalination is typically accomplished by distillation, reverse osmosis or electrodialysis. A common source water may be seawater.
DESIGN RATE OF FLOW (DESIGN FILTER RATE) The average rate of flow in a system which is used for design calculation (usually the flow in gallons per minute divided by the effective filter area in square feet).
DIALYSIS DEMENTIA A severe, often fatal encephalopathy which has been attributed to accumulation in the brain of aluminum from dialysate prepared with inadequately purified water. May include consumption of tap water with high levels of alum used in most municipal water treatment processes.
DIATOMACEOUS EARTH (D.E.) Porous silica from skeletal remains of one-celled plants, which when properly graded, acts as a precoat filter media for water filtration.
DIFFUSER A piece, adjacent to the impeller exit, which has multiple passages of increasing area for converting velocity to pressure in a pump.
DIRECTIONAL INLET FITTING An inlet fitting which provides adjustment in direction and flow rate to produce proper distribution of incoming water.
DISCHARGE Where the water exits the pump
DISCHARGE HEAD The total head, including static head and friction head, on the discharge side of the pump.
DISINFECTION A process for the destruction of bacteria. The process may be physical, as with heat or ultraviolet irradiation, or chemical, as with chlorination.
DISSOLVED SOLIDS (ALSO TOTAL DISSOLVED SOLIDS-TDS) Includes colloidal and suspended particles at sizes far less than one micron in diameter. Associated with evaporation process such as distillation.
DISTILLATION Steam from boiling water is condensed on a cool surface, collected and stored. Most contaminants do not vaporize and therefore do not pass to the condensate. Removes nearly 100 percent of salts and those organics that do not have a vaporizing temperature near or below that of water. Usually combined with carbon filtration to remove balance of remaining organics with vaporization temperatures below that of water.
DISTILLED WATER Water which has been purified by passing through an evaporation, condensation cycle; it generally contains less than 5 ppm of dissolved solids.
DISTRIBUTOR (TOP OR BOTTOM) The device in a filter designed to divert the incoming water to prevent erosion of the filter media.
DIVING AREA That area of a pool designed for diving. (NOTE: Diving Areas are defined in detail in various standards and regulations such as NSPI, Public and Residential Pool Standards, AAU, FINA, etc.).
DIVING BOARD A board especially designed to produce diver spring action when properly installed on an anchor (base) and fulcrum. (The term diving board includes non-spring types).
DIVING PLATFORM Usually used for the standard 5-meter and 10-meter official diving platform.
DIVING TOWER This term is usually used for the 3-meter (10-ft.) springboard support.
DRAIN An outlet at the deep point of a vessel or trough through which waste water passes.
DRAWDOWN The difference between the static water level and the pumping water level in a well. Also can refer to the per cycle capacity rating of a pressure tank at a given pressure range.
DRY NICHE A normal weatherproof fixture placed in an opening behind the pool wall which illuminates the pool through a watertight window in the pool wall.
[ E ]
ECCENTRIC The shape of a pipe or fitting meaning off-center, not exactly circular in shape.
EFFECTIVE FILTER AREA Permanent Medium Type: The effective filter area is the filter surface that is perpendicular to the flow direction. Cartridge Filter: The total effective filter area shall be the cartridge area that is exposed to the direct flow of water. This excludes cartridge ends, seals, supports and other areas where flow is impaired.
EFFLUENT The output stream exiting the system, filter or other device - often the waste stream.
EJECTOR A device consisting of a body, nozzle, and venturi tube that increases the pressure output of a jet pump. The nozzle increases the velocity of the water then the venturi tube converts the velocity to pressure.
ELECTROLYSIS Decomposition of metal due to flow of electrical current.
ELEVATION The vertical distance between the level where fluid enters a pipe and the level where it leaves. It must be added to the TOTAL DISCHARGE HEAD if the inlet is lower than the outlet and subtracted if the inlet is higher. As a rule of good installation practice, however, pipes should slope continuously upward from the inlet to the outlet to prevent entrapment of air.
EMPTY BED CONTACT TIME A measurement of the duration of contact between water and the media through which it is flowing, typically used in reference to carbon beds.
ENDOTOXIN Bacterial lipopolysaccharide, a substance released from the cell walls of gram-negative bacteria when the organism is broken down.
EQUILIBRIUM The condition where the forces applied to an object are in balance.
EXPLOSION PROOF A type of motor enclosure that will prevent sparks generated by the motor from reaching the atmosphere outside of the motor enclosure. As a general rule our company does not sell this kind of motor.
[ F ]
FACE PIPING The piping with all valves and fittings which is used to connect the filter system together as a unit. This includes all valves and piping necessary for the filter plant to perform the functions of filtering or backwashing, either by the plant as a whole or any unit operating singly.
FACTOR OF SAFETY The ultimate load divided by the safe load or the ultimate strength divided by the allowable stress.
FEED WATER Water under pressure entering a purification system or an individual piece of purification equipment, such as an ultra filter, distiller or reverse osmosis system.
FEET OF HEAD A basis for indicating the resistance in a hydraulic system, equivalent to the height of a column of water that would cause the same resistance (100 feet of head equals 43 pounds per square inch). The total head is the sum of all resistances in a complete operating system. The principal factors affecting a head are vertical distances and the resistance caused by friction between the fluid and pipe walls.
FERRIC IRON Small solid iron particles containing trivalent iron, usually as gelatinous ferric hydroxide or ferric oxide, which are suspended in water and visible as "rusty water". Ferric iron can normally be removed by filtration. Also called "precipitated iron".
FERROUS IRON A divalent iron ion, usually as ferrous bicarbonate which, when dissolved in water, produces a clear solution. It is usually removed by cation exchange water softening. Also called "clear water" iron.
FILTER A device that separates solid particles from water by recirculating the water through a porous substance (a filter medium element). Permanent Medium Filter: A filter that utilizes a medium that under normal use will not have to be replaced. Diatomaceous Earth Filter: A filter that utilizes a thin layer of diatomaceous earth as its filter medium that periodically must be replaced. Cartridge Filter: A filter that utilizes a porous cartridge as its filter medium.
FILTER AGITATION The mechanical or manual movement to dislodge the filter aid and dirt from the filter element.
FILTER AID A type of finely divided media used to coat a septum type filter, usually diatomaceous earth or volcanic ash. (NOTE: Alum, as used on the bed of a sand filter, is also referred to as a filter aid).
FILTER CARTRIDGE A filter which operates through a disposeable cartridge. These are of two general types: The surface or area type where the suspended matter is removed at the surface, and the depth type in which the interstices vary from large to small in depth.
FILTER CYCLE The operating time between cleaning or bachwash cycles.
FILTER DIATOMITE One designed to filter water through a thin layer of filter aid such as diatomaceous earth or volcanic ash. Diatomite filters may be of the Pressure, Gravity, Suction or Vacuum type.
FILTER ELEMENT A device within a filter tank designed to entrap solids and conduct water to a manifold, collection header, pipe or similar conduit. A filter element usually consists of a septum and septum support.
FILTER MEDIA The finely graded material which entraps suspended particles (sand, anthracite, diatomaceous earth, etc.).
FILTER ROCK Graded, rounded rock and/or gravel used to support filter media.
FILTER SEPTUM That part of the filter element consisting of cloth, wire screen or other porous material on which the filter cake is deposited.
FILTER, GRAVITY - SAND A filter with a layer of filter media (usually silica sand) supported on graded gravel through which water flows by gravity.
FILTER, PRESSURE - SAND A sand filter enclosed in a tank to operate under pressure.
FILTER, SAND A type of filter media composed of hard sharp silica, quartz, or similar particles with proper grading for size and uniformity.
FILTER, VACUUM (SUCTION) A filter which operates under a vacuum or from the suction side of a pump.
FILTRATE The portion of the feed stream that has passed through the membrane or filtering media.
FILTRATION FLOW The rate of flow in volume per time (gpm, gph), through the filter system installed per manufacturer’s instructions with a new, clean filter medium.
FILTRATION RATE The rate of filtration of water through a filter during the filter cycle expressed in US gallons per minute per square foot of effective filter area.
FINA The Federation Internationale de Natation Amateur – The governing body for intercollegiate competition including the Olympic games.
FLANGE A device used to couple to a pipe on the suction or discharge of a pump.
FLOCCULATING AGENT A compound, such as one of the alums, which forms minute flakes in water which attract or enmesh small suspended particles.
FLOCCULENT Chemical which, when added to water, causes particles to coagulate into larger, settleable groupings. Aluminum compounds are common catalysts in this process.
FLOOR SLOPE The slope in the pool floor, usually expressed in feet (or inches) of vertical rise in feet (or inches) of horizontal distance.
FLOW RATE OR CAPACITY The volume of liquid that passes a given point in a specified unit of time.
FLOW VELOCITY A quantitative expression of the rate of linear motion at which water passes through a pipe or conduit.
FLUIDIZATION A process by which particles are suspended by an upward flow of liquid, such as may occur during back washing of ion exchange resin or carbon media.
FLUORIDE A salt of hydrofluoric acid which may occur naturally in water supplies or be added by municipal processes for the prevention of dental caries. Fluoride is considered toxic in most medical settings and has been implicated with a wide range of physiological disorders including renal bone disease.
FLUX/FLUX RATE The rate per unit of area at which water passes through a semi-permeable membrane, such as those used for ultrafiltration or reverse osmosis.
FOOT VALVE A modified check valve that has a screen on the suction end to prevent debris from entering the pump or pipe.
FORCE The applied effort used attempting to move something.
FOULING The deposition of insoluble materials, such as bacteria, colloids, oxides and water-borne debris, onto the surface of a media such as water softening resins, reverse osmosis or ultrafiltration membrane. Fouling is associated with decreased flux rates and may also reduce the rejection rates of reverse osmosis membranes.
FREEBOARD The clear vertical distance between the top of the filter medium and the lowest outlet of the upper distribution system in a permanent medium filter.
FRICTION The resistance to motion by two objects or surfaces that touch.
FRICTION LOSS The loss of pressure or head due to the resistance to flow in the pipe and fittings. Friction loss is influenced by pipe size and fluid velocity, and is usually expressed in feet of head.
FULVIC ACIDS Acidic substances which are found in humic (organic) soils and which may become suspended in water. A component in the production of chloramines.
FUNGUS A parasitic plant which produces no chlorophyll and is dependent on other life forms for its existence.
[ G ]
GALVANIC ACTION Creation of an electrical current by electrochemical action.
GLAUCONITE SAND A mineral which is frequently used in depth filters.
GPD Gallons per day. A flow rate measurement
GPG Grains per gallon. Equivalent to 17.1 milligrams/liter of calcium carbonate.
GPH Gallons per Hour flow rate measurement
GPM Gallons Per Minute / Rated capacity of a pump
GREY WATER Wastewater from household baths and washing machines that is sometimes recycled especially for use in gardening or for flushing toilets.
GUTTER FITTING (GUTTER DRAIN) A drainage fitting used in the overflow gutter.
[ H ]
HANDHOLD/HANDRAIL A permanently installed device that can be gripped by a bather for the purpose of resting and/or steadying him/herself. Is not limited to but may be located within or without the pool, spa or hot tub or as part of a set of steps or deck-installed equipment.
HARDNESS The amount of calcium and magnesium in the water in grains per gallon, (expressed as calcium carbonate). This level is important to control during distillation or reverse osmosis processes to prevent scaling. Each grain is equal to 17.1 ppm of calcium and magnesium (expressed as calcium carbonate). What constitutes truly "hard" water is subject to much debate and controversy. Proponents of water softening systems tend to call water "hard" which contains between 3 and 10 grains of hardness. This definition is supported by the American Society of Agricultural Engineers and the Water Quality Association, major supporters of the water softening industry. Water with 10 grains of hardness, is regularly used by consumers, with little or no adverse affect on plumbing or other household functions. Water, which approaches 15 to 20 grains is more in line with situations which require water softening or conditioning. Water with 3 grains of hardness and is termed "moderately hard" by these organizations is typically found in surface and spring water sources, far removed from what one would consider hard water sources.
HEAD A term used to define water pressure in vertical feet. Or a term representing the energy content of a liquid, expressed as the height of an equivalent vertical column of water. a. This is expressed in feet of head. b. This can apply to both sides of a pump; the suction side and discharge side. c. It is also used to express the total losses in a pumping system (Total Dynamic Head).
HEAVY METALS Metals having a high density or specific gravity. A generic term used to classify contaminants such as cadmium, lead and mercury. These contaminants can damage living things even at low concentrations and tend to accumulate in the food chain.
HERMETIC Completely sealed, especially against the escape or entry of air.
HI-RATE PERMANENT MEDIA FILTER A filter using high velocity
HOMOGENEOUS MEMBRANES See membranes.
HORIZONTAL RUN The horizontal distance between the point where fluid enters a pipe and the point at which it leaves.
HOSE CONNECTOR The fitting used to connect the hose to the vacuum wall fitting (usually a combination hose sleeve and nut).
HOT TUB A spa constructed of wood with sides and bottom formed separately; and the whole shapes to join together by pressure from the surrounding hoops, bands or rods; as distinct from spa units formed from plastic, concrete, metal or other materials.
HYDRAULIC SHOCK A damaging condition that occurs when a column of liquid changes direction quickly and increases in velocity. Weakest point in system will break. Causes can be sudden loss of power to the driver, valve closing too quickly, valve closing too slowly allowing backflow.
HYDROGEN SULFIDE A toxic gas that is detectable by a strong "rotten egg" odor. Associated with high levels of bacterial decay. Commonly found together with iron and manganese contaminants.
HYDROJETS A fitting that bleeds air and water creating a high velocity, turbulent stream of air enriched water.
HYDROLOGIC CYCLE The term used to describe how water travels through the environment by evaporation, condensation and precipitation. Identical process is observed in steam distillation systems.
HYDROLYSIS A chemical process resulting from reactions with water; frequently used in reference to the breakdown of polymers.
HYDROPHILIC Pertaining to a substance, which readily absorbs water ("water-loving").
HYDROPHOBIC Pertaining to a substance, which does not readily absorb water ("water-hating").
HYDROTHERAPY INLET FITTING A special high velocity air entraining inlet fitting to produce a massage effect.
HYDROTHERAPY SPA OR HOT TUB A unit that may have a therapeutic use which is not drained, cleaned or refilled for each individual. It may include, but not be limited to, hydrojet circulation, hot water and cold water mineral baths, air induction bubbles or any combination thereof. Industry terminology for a spa includes, but is not limited to, “therapeutic pool,” “hydrotherapy pool,” “whirlpool,” “hot spa,” etc.
HYPOCHLORINATOR A device used to feed, control and measure a solution of sodium or calcium hypochlorite into a water being treated. There are three general types: The positive displacement type which is usually a motor driven unit, the aspirator type actuated by a pressure differential created within the hydraulic system, and the metering type connected to the pump suction using an orifice which is opened and closed by a timing mechanism.
HYPOCHLORITE A chemical compound commonly found in two forms for use with pools, spas and hot tubs: calcium hypochlorite is a chlorine carrier in both granular and solid form normally containing 70% to 80% available chlorine by weight; sodium hypochlorite is a liquid chlorine carrier normally containing 5% to 16% available chlorine by weight.
HYPOCHLORITE, CALCIUM A compound of chlorine and calcium used in powder or granulated form usually containing 70% to 80% available chlorine by weight which is released in water solution to act as a germicide or algaecide.
HYPOCHLORITE0, SODIUM A compound usually containing 5% to 16%, or more, available chlorine by weight, in a caustic soda solution, which releases chlorine when added to pool water.
[ I ]
IMPELLER The bladed member of the rotating assembly of the pump which applies the principal force to the liquid being pumped.
INFLUENT The inflow or entering water to a filter or other device.
INLET The fitting through which the filtered water passes to the pool (filtered water inlet), or the fitting through which raw water passes to the pool (raw water inlet).
IODINE An element related to chlorine and bromine used as a disinfectant, both in its natural solid form and in iodide compounds. When iodides are used, chlorine is normally employed to free the elemental iodine.
ION An atom or molecule having either a positive or negative electrical charge. Positively charged ions are referred to as cations and ions having a negative charge are termed anions.
ION EXCHANGE A process by which certain ionized chemicals present in water are replaced with other ionized chemicals temporarily attached to resin particles. The exchange process is made only for ions having the same charge.
IRON A very common element often present in ground water in amounts ranging from 0.01 to 10.0 ppm(mg/l). Iron may be found in three forms: in soluble forms such as in ferrous bicarbonate; bound with a soluble organic compound; or as suspended ferric iron particles. Iron above 0.3 mg/l is objectionable to water because of staining of laundry and plumbing fixtures.
IRON BACTERIA Bacteria which thrive on iron and are able to actually use ferrous iron (as found in water or steel pipes) in their metabolic processes to incorporate ferric iron in their cell structure and to deposit gelatinous ferric hydroxide iron compounds in their life processes.
[ J ]
JET PACKAGE An accessory kit sold with jet pumps. Can consist of ejector, extra nozzles and venturis, bushings and reducers, pipe adapters and foot valves, and packing leathers. Also known as Ejector package or Injector package.
JET PUMP A centrifugal pump used in conjunction with an ejector to provide higher pressure.
JTU (JACKSON TURBIDITY UNIT) A visual means of measuring water clarity based upon the amount of light passing through a tube of water.
JUMP BOARD A mechanism that has a coil spring, leaf spring or comparable device located beneath the board which is activated by the force exerted in jumping on the board.
[ K ]
No Terms Found
[ L ]
LADDER, DECK A ladder for deck access from outside the pool, spa or hot tub.
LADDER, DOUBLE ACCESS A ladder that straddles the pool wall of an aboveground pool and provides pool ingress and egress.
LADDER, LIMITED ACCESS Any ladder with provision for making entry inaccessible when a pool, spa or hot tube is not in use (i.e., swingup, slide-up or equivalent).
LAMINAR Non-turbulent fluid flow. Associated with fluid dynamics and designs of fluid tubing and pipelines.
LANGELIER SATURATION INDEX A calculated number used to predict the calcium carbonate (CaCO3) stability of a water; whether a water will precipitate, dissolve, or be in equilibrium with, calcium carbonate. It is sometimes erroneously assumed that any water that tends to dissolve calcium carbonate is automatically corrosive. Langelier saturation index = pH - pH, where pH = actual pH of the water, and pH, = pH at which the water having the same alkalinity and calcium content is just saturated with calcium carbonate.
LIGNIN A polysaccharide found in the cell walls of plants; a breakdown product of decaying vegetation, which may be present in surface water supplies.
LINER That membrane that acts as a container for the water.
LINER, EXPANDABLE A liner that is constructed of a material that has the capability of stretching into a greater depth of irregular shape other than the original construction dimensions.
LINER, HOOPER The liner that is used to obtain greater depth by geometrical pattern construction on the liner bottom or floor to fit a predetermined size and shape.
LOWER DISTRIBUTION SYSTEM (UNDERDRAIN) Those devices used in the bottom of a permanent medium filter to collect the water during the filtering and to distribute the water during the backwashing.
[ M ]
MAIN OUTLET The outlet fitting at the bottom of a swimming pool through which water passes to the recirculating pump (often erroneously referred to as the “main drain”.
MAKE-UP WATER Fresh water used to fill or refill the pool, spa or hot tub.
MEMBRANES Thin films constructed of cellulosic or synthetic materials, which are designed to provide selective transport of solutes. Widely used for hemodialysis, micro filtration, ultrafiltration and reverse osmosis, membranes may be either homogeneous or asymmetric. Homogeneous membranes have a uniform structure or cross-section while asymmetric membranes have a dense "skin" which overlays a porous substructure.
METHEMOGLOBINEMIA The presence in blood of methemoglobin, a substance related to normal oxyhemoglobin, but having no oxygen-carrying capabilities and induced by exposure of blood to certain toxic chemicals, such as nitrites.
Mg/l Milligrams per liter. A measure of concentration of a dissolved substance in a liquid. A concentration of one mg/l means that one milligram of a substance is dissolved in each liter of water. For practical purposes, this unit is equal to parts per million (ppm) since one liter of water is equal in weight to one million milligrams. Thus, a liter of water containing 10 milligrams of calcium has 10 parts of calcium per one million parts of water or 10 parts per million (10 ppm).
MICRO FILTRATION The separation or removal from a liquid of particulates and micro-organisms in the size range of 0.1 to 2 microns in diameter.
MICRO POROUS In the context of water purification, membranes having an average pore size, which is between 0.1 and 1.0 micron in diameter.
MICROFARAD A measurement of capacitance (electrical storage capability). Capacitors or condensers have a range listed on the casing (15-22 MFD, example) showing the capacity it can handle. They will also show the maximum voltage they can handle (370V, example).
MICROHM One millionth of an ohm. The unit of measurement for testing the electrical resistance of water to determine its purity. The closer water comes to absolute purity, the greater its resistance to conduction of an electrical current. Absolute pure water has a specific resistance over 18 million ohms (megohms) across one centimeter of water at a temperature of 78 degrees Fahrenheit.
MICRON A unit of linear measure. It is one millionth of a meter, or one thousandth of a millimeter. The smallest particle than can be distinguished by the naked eye would be about 40 microns across.
MICRON RATING A measurement applied to filters or filter media to indicate the particle size at which a substantial percentage of suspended solids above that size will be removed. As used in the water treatment industry standards, this may be an absolute rating or a nominal rating.
MICRONS A measurement used in filtration. A millionth part of a specified substance.
MICROWATT-SECONDS PER SQUARE CENTIMETER A unit of measurement of intensity and retention, or contact time in the operation of ultraviolet (U/V) systems.
MILLILITERS/MINUTE A common measurement for the flow rate of small RO systems. Usually measured with a graduate cylinder. One thousandth of a liter per minute. Milliliters/min x.38 = gal/day.
MIXED BED The intermixing of two or more filter or ion exchange products in the same vessel during a service run. The most common use is in ion exchange systems having a 40/60 percent cation to anion resin bed such as that for a deionization polisher system. In filtration, there may be an intermixing of two or more media in a single tank with each stratified into separate layers.
MOD MEDIA Short for Modular Media, a type of filtration system. Consists of filters within filters - interchangeable and replaceable.
MODEL NUMBER Identification nomenclature for a product.
MONOVALENT ION A cation or anion having a single electrical charge.
MSDS Material Safety Data Sheet - Required by law for products with potential for pollution or health risks(examples = paint, petroleum products).
MTBE:(Methyl Tertiary Butyl Ether) A volatile organic chemical (VOC) used as an octane-enhancing lead substitute and more recently as an oxygenating agent in gasoline to reduce carbon monoxide emissions from automobiles. MTBE is volatile, flammable and highly soluble in water. During refueling and gasoline production, MTBE is volatilized to the atmosphere where it dissolves into the atmospheric moisture and returns to earth as precipitation, polluting our water supplies. Since MTBE does not adsorb well with organic matter in soils it is easily washed away. In surface water, MTBE volatilizes into the air. While in ground water, MTBE persists and moves freely. MTBE occurrences in ground water above 40 ppb have so far been attributed to point source contamination such as underground gasoline tank leaks, overflows, etc. EPA has tentatively classified MTBE as a potential human carcinogen.
MULTIPLE FILTER CONTROL VALVE A multi-port valve with at least four positions for varous filter operations, which combines in one unit the function of two or more single direct flow valves (Dial Selector Valve).
MURIATIC ACID A commercial name for hydrochloric acid. Used for lowering the pH and alkalinity of pool water.
[ N ]
NANOFILTRATION A membrane treatment process, which falls between reverse osmosis and ultrafiltration on the filtration/separation spectrum. The nanofiltration process can pass more water at lower pressure operations than reverse osmosis, can remove particles in the 300 to 1,000 molecular weight range such as humic acid and organic color bodies present in water, and can reject selected (typically polyvalent) salts. Nanofiltration may be used for selective removal of hardness ions in a process known as membrane softening.
NCAA National Collegiate Athletic Association – The governing body for intercollegiate competition and the recording agent for college swimming records.
NEMA National Electrical Manufacturers Association
NET POSITIVE SUCTION HEAD REQUIRED The amount of head required by the pump to keep a fluid in a liquid state.
NEUTRALIZATION The addition of either an acid to a base or a base to an acid to produce a more nearly neutral solution. The use of alkaline or basic materials to neutralize acidity of some water is common practice in water processing to prevent corrosion of metallic home plumbing.
NITRATE An anion comprised of one nitrogen atom and three oxygen atoms. Nitrates are considered toxic in hemodialysis water and are also harmful to infants when consumed orally.
NOMINAL FILTER RATING Filter rating indicating the approximate size particle, the majority of which will not pass through the filter. It is generally interpreted as meaning 85 percent of the particles of the size equal to the nominal filter rating will be retained by the filter.
NONSWIMMING AREA Any portion of a pool, spa or hot tub where water depth, offset ledges or similar irregularities would prevent normal swimming activities.
NOZZLE An ejector part/device that increases the velocity of the liquid flowing through it by creating a partial vacuum at it's throat. Atmospheric pressure causes the increase in velocity.
NPS DISCHARGE Nonpoint Source pollution: nutrients,. sediments, toxic substances, and pathogens that degrade waterways. NPS occurs mainly through stormwater runoff.
NPSH Net Positive Suction Head. There are two types of NPSH. NPSHR is the amount of head required by the pump to keep the liquid being pumped in a liquid state. The only way NPSHR can be changed is by changing the pumps' rotational speed or its impeller diameter. NPSHA is the amount of head available to the pump to overcome the NPSHR. NPSHA should be a larger number than NPSHR. NPSHA is affected by atmospheric pressure changes, altitude, pipe and fitting sizes, and elevation to the liquid being pumped.
NSF National Science Foundation.
NTU (NEOPHELOMETRIC TURBIDITY UNIT) An instrumental means of measuring water clarity based upon the intensity of light scattered by suspended particles.
[ O ]
ODP Open Drip Proof - a type of motor enclosure
OPERATING PRESSURE The manufacturer's specified range of pressure expressed in pounds per square inch (PSI) in which a water processing device or water system is designed to function.
OPERATING TEMPURATURE The manufacturer's recommended feed water or inlet water temperature for a water treatment system.
ORIFICE PLATE A disc, placed in a water flow line, with a concentric sharp-edged circular opening in the center, which creates a differential pressure to measure flow and to operate feeders and instruments or other hydraulic equipment.
OSMOSIS The natural tendency of water to pass through a semi-permeable membrane, so as to equalize concentrations on both sides of the membrane.
OSMOTIC PRESSURE The force (pressure) resulting when two liquids, having different solute concentrations, are separated by a semi-permeable membrane. For every 100 ppm, an osmotic "back pressure" of 1 psi is generated and this "back pressure" must be overcome in the reverse osmosis process.
OSTEODYSTROPHY Abnormal bone development which, in renal patients, may be attributed to parathyroid gland dysfunction and is characterized by high serum phosphorus and alkaline phosphates and low serum calcium levels.
OSTEOMALACIA Abnormal bone development which, in renal patients, may be attributed to parathyroid gland dysfunction and is characterized by high serum phosphorus and alkaline phosphates and low serum calcium levels.
OSTEOPOROSIS Demineralization of bone, which may cause fractures with minimal stress.
OVERFLOW GUTTER The gutter around the top perimeter of the pool which is used to skim the surface of the water and to carry off the waste, or to collect it for return to the filters (sometimes incorrectly referred to as “scum gutter” or “spit trough”).
OVERFLOW SYSTEM Refers to removal of pool surface water through the use of overflows, surface skimmers and surface water collection systems of various design and manufacture.
OXIDANTS (OXIDIZING AGENTS) Chemicals, which provide oxygen and accept an electron in an oxidation-reduction reaction. Free chlorine and chloramines are oxidants, which are widely used for disinfection.
OXIDIZING FILTERS Filters that use a catalytic media, such as managanous oxides or potassium permangenate, to oxidize iron, manganese and other impurities from water.
OZONE An extremely active oxidizing agent and bacteriocide, which consists of three oxygen atoms. It is formed by the action of a high voltage electrical field on oxygen or air (such as occurs during an electrical storm). Some degree of ozone can also be produced by certain types of ultraviolet lamps.
[ P ]
PARTS PER MILLION (ppm) The standard measure of total dissolved solids. Parts of dissolved material in one million parts of water. (eg. one pound of mineral salts dissolved in a million pounds of water would be on part per million).
PASCAL (pa) A unit of pressure equal to one newton of force per square meter. One thousand pascals equal one kilopascal (KPa); a kilopascal equals 0.145 pounds per square inch. Alternatively, 1 psi = 6895 Pa = 6.895 kN/sq.m = 0.0703 kg/sq.cm.
PATHOGENS Micro-organism that can cause disease in other organisms or in humans, animals and plants. They may be bacteria, viruses or parasites and are found in sewage, in runoff from animals and in water used for swimming. Fish and shellfish contaminated by pathogens, or the contaminated water itself, can cause serious illness.
PERMEABLE Allowing some material to pass through.
pH A measurement of water acidity or alkalinity using a scale of 0 to 14. 7 = neutrality, numbers less than 7 = acidity, numbers greater than 7 = alkalinity. Relative acidity or alkalinity of a substance, such as water, as indicated by the hydrogen ion concentration.
PHENOLS Weak aromatic acids, which are indicative of industrial pollution of water supplies. When combined with chlorine, they produce an objectionable taste and odor.
PINCHING HAZARD Any configuration of components that would pinch or entrap the fingers or toes of a bather.
POLYAMIDE A synthetic polymer of the nylon family used in the fabrication of reverse osmosis and ultrafiltration membranes.
POLYMERS A chemical compound with many repeating structural units.
POLYSULFONE A synthetic polymer used to fabricate reverse osmosis and ultrafiltration membranes, which are characterized by extreme thermal stability and chemical resistance. Popular in dental waterline filtration systems.
POLYVALENT ION A cation or anion having a multiple electrical charge.
POLYVINYL CHLORIDE A thermoplastic piping material produced by the polymerization of vinyl chloride.
POOL BOILER A type of pool heater operating as an Indirect Type, but using steam instead of hot water in the closed system.
POOL DEPTH The vertical distance between the floor level and or which is inclined 45° or less from horizontal. The normal or operating water level when the pool is in use.
POOL FLOOR That portion of the pool interior which is horizontal or which is inclined 45° or less from horizontal.
POOL HEATER A device through which pool water is circulated to increase the temperature of the water. In the Direct Type, the heat is transferred directly to the pool water circulating tubes. The Indirect Type utilizes a separate enclosed system which is directly exposed to heat generator and which heats the pool water by circulating the steam or hot water around the tubes of a heat exchanger through which the water circulates. The heat generator is considered part of every heater.
POOL WALL The sides of a pool above the floor which are vertical at the top and coved at the bottom, or which are inclined to the pool no more than 45° from the vertical.
POOLS - Above ground/Portable Swimming Pool A removable pool of any shape that is deeper than forty-two inches (42”) or holds more than 2,500 gallons of water or has a water surface area in excess of 150 square feet. The aboveground pool frame is located entirely above ground and may be readily disassembled for storage and reassembled to its original integrity.
POOLS - In Ground Swimming Pool Any pool, spa or hot tub whose sides rest in partial or full contact with the earth.
POOLS - Non-Permanently Installed Swimming Pool One that is so constructed that it may be readily disassembled for storage and reassembled to its original integrity.
POOLS - On-Ground Swimming Pool Any pool, spa or hot tub whose sides rest fully above the surrounding earth and that has a deep area below the ground level.
POOLS - Public Any pool, other than a residential pool, which is intended to be used for swimming or bathing and is operated by an owner, lessee, operator, licensee or concessionaire, regardless of whether a fee is charged for use.
POOLS - Public Class A - Competition Any pool intended for use for accredited competitive aquatic events such as FINA, AAU, NCAA, N.F., etc. The pool may also be used for recreation.
POOLS - Public Class B Any pool intended for public recreational use.
POOLS - Public Class C Any pool operated solely for and in conjunction with lodgings such as hotels, motels, apartments, condominiums, etc.
POOLS - Public Class D - Special Purpose Any pool operated for medical treatment, water therapy or nonrecreational functions.
POOLS - Public Type VI thru Type X Public Pools suitable for the installation of diving equipment by type. Diving equipment classified at a higher type may not be used on a pool of lesser type (i.e., Type VIII equipment on a Type VI pool).
POOLS - Residential A residential pool shall be defined as any constructed pool, permanent or nonportable, that is intended for noncommercial use as a swimming pool by not more than three-owner families and their guests and that is over twenty-four inches (24”) in depth, has a surface area exceeding 250 square feet and/or a volume over 3,250 gallons. Residential Pools shall be further classified into types as an indication of the suitability of a pool for use with diving equipment.
POOLS - Residential - Type I thru Type V Diving Equipment Residential pools suitable for the installation of diving equipment by type. Diving equipment classified at a higher type may not be used on a pool of lesser type (i.e., Type III equipment on a Type II pool).
POOLS - Residential - Type Q Any residential pool where the installation of diving equipment is prohibited.
POOLS - Wading A pool that may range in water depth from two feet (2’) to zero feet (0’) for wading.
PORE An opening in a membrane, which allows certain components to pass through, but not others.
POTABLE WATER Any water, such as an approved domestic water supply, which is bacteriologically safe and otherwise suitable for drinking.
POTASSIUM PERMANGANATE An oxidizing agent commonly used for the regeneration of manganese green sand iron filters and occasionally used as a disinfectant.
POWER The rate at which work is expended.
PPB Parts per billion (equivalent to micrograms per liter)
PPM Parts per million (equivalent to milligrams per liter).
PPM (PARTS PER MILLION) Unit used for the measurement of the concentration of a chemical or other substance in the pool, spa or hot tub water, where this concentration is expressed in terms of “n” molecules of substance per one million molecules of water.
PRECHARGE The air put into a pressure tank to make it operate within a specific pressure range
PRECHARGED TANK A water storage tank pre-charged with air at factory featuring a vinyl bag to separate water from air which prevents waterlogging. This tank design provides greater drawdown than standard tanks. Pre-charged tanks do not require air volume control.
PRECOAT The coating of filter aid on the septum of a diatomite type filter at the beginning of each filter cycle.
PRECOAT FEEDER A device used to feed a calculated amount of filter aid at the start of a diatomaceous earth filter cycle - following the cleaning operation.
PREMEATE See product water.
PRESSURE The effect produced by the application of force over the surface of an area.
PRESSURE DIFFERENTIAL The difference is pressure between two parts of a hydraulic system (influent and effluent of a filter, suction and discharge of a pump, the up and down-stream sides of a venturi or orifice).
PRESSURE DROP Sometimes referred to as "delta P", it is the decrease in hydrostatic force (pressure) due to the effects of friction or restrictions on a flowing liquid.
PRESSURE HEAD The vertical distance (in feet) equal to the pressure (in PSI) at a specific point. The pressure head is equal to the pressure in PSI times 2.31 ft.
PRIORITY POLLUTANTS Those pollutants that pose the most serious health hazards determined by the EPA (Environmental Protection Agency).
PRODUCT WATER The purified water stream from equipment, such as distillation, reverse osmosis and ultra filter units.
PSI An abbreviation for “pounds per square inch” (see “Feet of Head”).
PUMP STRAINER A device, placed on the suction side of a pump, which contains a removable strainer basket designed to trap debris in the waterflow with a minimum of flow restriction (sometimes referred to in the past as a “Hair and Lint Trap”).
PUMPING LEVEL The lowest water level reached during pumping operation.
PUNCTURE HAZARD Any surface or protrusion that would puncture a bather’s skin under casual contact.
PYROLOSIS A breakdown process which occurs when organic matter is subjected to elevated temperatures.
[ Q ]
QUATERNARY AMMONIA A series of compounds of ammonia in solution used as algaecides and germicides which reduce the surface tension of the water.
[ R ]
RADIAL FLOW The flow pattern in which water flows from the outside of a filter element to the center core. For example, a replaceable particulate or carbon cartridge filter unit.
RATE OF FLOW (GPM) The measurement of the volume of flow per unit of time expressed in gallons per minute.
RATE OF FLOW INDICATOR A device to indicate the rate of flow in a pipe line (sometimes referred to as a “rate-of-flow meter”).
RATED PRESSURE That pressure that is equal to or less than the designed pressure and appears on the dataplate of the equipment.
RECIRCULATING SYSTEM The entire system including the suction piping, pump, strainer, filter, face piping and return piping.
RECOVERY (PERCENT RECOVERY) A measurement applied to distillation, reverse osmosis and ultrafiltration equipment, which characterizes the ratio of product water to feed water flow rates. The measurement is descriptive of distillation reverse osmosis or ultrafiltration equipment as a system and not of individual membrane elements. Expressed as a , recovery is defined as: % Recovery = (Product flow rate/Feed flow rate) x 100.
REGENERATION Carried out using either an acid or alkali to remove the accumulated cations or anions, respectively from a filtration media. At the same time, the cation exchanger takes on hydrogen ions, to restore them to the original hydrogen or hydroxide form, respectively.
REJECTION (PERCENT REJECTION) A measure of the ability of a reverse osmosis membrane to remove salts. Expressed as a percentage, rejection is defined as: Rejection = (l-Product concentration/Feed concentration) x 100.
REMOVABLE Capable of being disassembled with the use of only simple tools such as a screwdriver, pliers or wrench.
RESIDUAL Usually refers to chlorine residual, or the amount of measurable chlorine remaining after treating water with chlorine. Free residual differs from combined residual in that it is not combined with ammonia or other elements or compounds, and is a more effective disinfectant.
RESIN Specially manufactured polymer beads used in the ion exchange process to remove dissolved salts from water.
RETURN PIPING That part of the pool, spa or hot tub piping between the filter and the vessel through which filtered water passes.
REVERSE OSMOSIS A reversal of the natural phenomenon of osmosis brought about by application of hydraulic pressure greater than the osmotic pressure in water (containing dissolved solids) to cause the water molecules to flow through the membrane away from the dissolved substances.
RO Reverse Osmosis-a method of water treatment.
RYZNAR INDEX A modification of the Langelier index used to calculate the degree of calcium carbonate saturation and to predict the likelihood of scale formation from a water supply.
[ S ]
SAFETY LINE A continuous line not less than 1/4 inch in diameter, which is supported by buoys and attached to opposite sides of a pool which is supported by buoys and attached to opposite sides of a pool to separate the deep and shallow ends.
SALT PASSAGE RATE A measurement of the passage of salts through a reverse osmosis membrane. Salt passage is related to rejection by: % Salt passage = 100 - % Rejection.
SCALING Usually used in reference to distillation or reverse osmosis equipment, scaling is the precipitation of sparingly soluble salts, such as calcium carbonate, onto the surface of a distiller boiler or reverse osmosis membrane. Scaling is associated with decreased flux and reduced reverse osmosis rejection rates. Scaling also effects to a slight degree the efficiency of distillation processes.
SEDIMENT Very small debris, such as sand, rust, or silt.
SEDIMENTATION The process by which solids are separated from water by gravity and deposited on the bottom of a container or basin.
SELF PRIMING A pump designed to have the ability to prime itself automatically, after being initially filled, when operating under a suction lift; to free itself of entrained gas without losing prime; and to continue normal pumping operation without attention.
SEMIPERMEABLE Descriptive of a material, such as a reverse osmosis or ultrafiltration membrane, which allows the passage of some molecules and prevents the passage of others.
SEPTUM That part of the filter element consisting of cloth, wire screen or other porous material on which the filter medium or aid is deposited.
SERVICE FACTOR A factor indicating the degree to which an electric motor can be operated over the specified horsepower without danger of overloading or failure.
SERVICE PRESSURE The range of pressure in the pressure tank during the pumping cycle, usually expressed in pounds per square inch gauge (P.S.I.G.).
SETTING The vertical distance from the level at which the discharge pipe leaves the well to the bottom of the pump or jet assembly in the well.
SHUT-OFF HEAD The head created by a pump that is running against a closed discharge.
SILT DENSITY INDEX A measurement of the rate at which a 0.45 ~m filter disc is plugged under standardized test conditions. Silt density index (SDI) determinations are used to estimate the rate at which various water supplies will cause fouling or plugging of reverse osmosis or ultrafiltration membranes.
SILVER PROTEIN A solution containing silver ions, such as Argyrol, used as a germicide.
SKIMMER WEIR The horizontal surface over which the water flows to the circulating system (usually self-adjusting for water level changes).
SLIP RESISTING A surface that has been so treated or constructed as to significantly reduce the chance of a bather from slipping. The surface should not be an abrasion hazard.
SLURRY A suspension of diatomaceous earth in water used for body feeding in D.E. filters.
SLURRY FEEDER A device to feed a variable amount of filter aid during the filter cycle.
SODIUM BISULFATE A dry chemical commonly used to lower pH in water. Also called soda ash.
SODIUM CARBONATE A dry chemical commonly used to raise pH in water.
SOFT WATER Water containing less than 1 grain per gallon dissolved calcium and magnesium salts. Definition of where “softness” starts may vary depending on individual viewpoints
SOLUTE Dissolved particles in a solvent
SORBENT See adsorption.
SPA A hydrotherapy unit of irregular or geometric shell design. (SEE “HYDROTHERAPY SPA” OR “HOT TUB”)
SPA - INGROUND A Spa whose sides reside partially or fully below the natural ground level.
SPIRAL WOUND MEMBRANE The most common practical configuration of membranes for RO systems.
SPRAY RINSE, MECHANICAL A fixed or mechanically movable spray system which directs a stream of water against the filter surface, causing the filter aid and accumulated dirt to dislodge into the empty tank.
SPRINGBOARD A board especially designed to produce diver spring action when properly installed on an anchor (base) and fulcrum. (The term diving board includes non-spring types).
STATIC HEAD The vertical distance between the free level of the source of the supply and the point of free discharge, or to the level of the free surface of the discharged water.
STATIC OR STANDING WATER LEVEL The undisturbed level of water in the well before pumping.
STEPS Riser/tread or series of risers/treads extending down from into the deck with the bottom riser/tread terminating at the pool
STERILIZATION A physical or chemical process that reduces the number of organisms to a safe predetermined level (see also disinfection).
SUBMERGENCE The vertical distance between PUMPING LEVEL and the bottom of the pump or jet assembly. Submergence must be sufficient to insure that the suction opening of the pump or jet assembly is always covered with water, while maintaining enough clearance from the bottom of the well to keep it out of sediment (at least 10 feet clearance is recommended).
SUCTION Where the water enters the pump
SUCTION HEAD The total head on the suction side of the pump, including suction lift and friction head.
SUCTION LEAK An escape of liquid from, or insertion of air into, the piping system going into a pump.
SUCTION PIPING That part of the pool, spa or hot tub piping through which water passes from the vessel to the pump.
SUPERFICIAL VELOCITY A quantitative expression of the rate of linear motion with which water passes through a vessel used to house particles, such as ion exchange resin or carbon media.
SURFACE SKIMMER Sometimes called a Recirculating Overflow. A deviced designed to continuously remove surface film and water and return it through the filter as part of the recirculation system, usually incorporating a self-adjusting weir, a collection tank and a means to prevent air lock of the pump (sometimes referred to as a “recirculation overflow,” or a “mechanical” or “automatic skimmer”).
SURFACE SKIMMER SYSTEM This term encompasses perimeter type overflows, surface skimmers and surface water collection systems of various design and manufacture.
SURGE CHAMBER A storage chamber within the pool recirculating system used to absorb the water displaced by bathers.
SURGE TANK A type of pressurized water storage vessel. Surge tanks typically have large areas of stagnation that offer opportunistic bacteria a favorable environment for multiplication. Commonly found in reverse osmosis systems. Requires periodic sanitation to ensure control of bacterial growth.
SUSPENDED SOLIDS Includes settle-able particles less than one micron in diameter.
SWIMMING AREA That area of a pool in excess of 3 feet in depth which is devoted to swimming.
[ T ]
TAMPERPROOF Meaning that tools are required to alter or remove portions of the equipment.
TANNIN Any of a group of water soluble, natural organic phenolic compounds that are produced by metabolism in trees and plants and are part of the degradation-resistant fulvic acid materials formed during the decomposition of vegetation. Tannins occur in water or in almost any location where large quantities of vegetation have decayed. Tannins can impart a faintly yellowish to brown color to water. Tannin molecules tend to form anions in water above pH 6 and can be treated with anion exchange resins. Below pH 5, tannins are better treated with activated carbon.
TASTE AND ODOR A type of filter that makes water smell and taste better.
TDH Total Dynamic Head
TDSL Total Dynamic Suction Lift
TEFC Totally Enclosed Fan Cooled - a type of motor enclosure
THIN FILM COMPOSITE A membrane made with a polyamide-based polymer consisting of three layers: a polyester support web, a micro porous polysulfonic inter layer, and an ultra-thin barrier coating on the top surface.
TITRATABLE ALKALINITY The quantity of hydrogen ions (H+), which must be added to a sample of alkaline water in order to establish a condition of neutrality.
TORQUE A twisting or turning effort that results from a force being applied to a rigid object at a radial distance from the center of rotation.
TOTAL DISCHARGE HEAD The total pressure or head the pump must develop on the discharge side. It is the sum of THE ELEVATION, THE SERVICE PRESSURE, and THE FRICTION LOSS. Of course, all of these measurements must be expressed in the same units, usually feet of head, before adding them together.
TOTAL DISSOLVED SOLIDS The sum of all ions in a solution, often approximated by means of electrical conductivity or resistance measurements. Total dissolved solids (TDS) measurements are commonly used to assess distiller and reverse osmosis unit performance. It is important to note that a test measuring the electrical conductivity of the water sample provides only an estimate of the TDS present, as conductivity is not precisely proportional to the weight of an ion and nonconductive substances cannot be measured by electrical tests.
TOTAL ORGANIC CARBON A measurement of the total mass of dissolved carbon in a water sample, excluding that originating from carbon dioxide and carbonates.
TOTAL SUSPENDED SOLIDS The particles, which can be removed from a solution by filtration, usually specified as the matter which will not pass through a 0.45 micron pore-diameter filter.
TOXIC Meaning that a given substance has an adverse physiological affect on man.
TREAD CONTACT SURFACE Foot contact surfaces of a ladder, step, stair or ramp.
TREADS, RECESSED A series of vertically spaced cavities in the pool, spa or hot tub wall creating tread areas for step-holes.
TURBIDITY A measurement of the amount of suspended solids (colloids) in a solution. Caused by stirred-up sediment, silt, clay, etc. Turbidity blocks light rays and makes the water opaque. Turbidity is measured in nephelometric turbidity units (NTU). Potable water should not exceed 0.3 NTU. Turbidity cannot be directly equated to suspended solids because white particles reflect more light than dark-colored particles and many small particles will reflect more light than an equivalent large particle.
TURNOVER The period of time (usually in hours) required to circulate a volume of water equal to the pool, spa or hot tub capacity.
[ U ]
ULTRA FILTERS A membrane based filtration system in which the pore sizes range from 0.002 to 0.1 microns.
ULTRAVIOLET (UV) LIGHT Radiation (light) having a wavelength shorter than 3900 angstroms, the wavelength of visible light and longer than 100 angstroms, the wavelengths of x-rays. This wavelength puts ultraviolet light at the invisible violet end of the light spectrum. UV light is used as a disinfectant. Water treated by ultraviolet light should be free from particulate materials or turbidity so as to prevent micro-organisms from being shielded from the incident UV radiation.
UNDERDRAIN The distribution system at the bottom of the filter which collects the water uniformly during the filter cycle, and which distributes the backwash water uniformly during the cleaning operation. Normally applies to sand filters.
UNDERWATER LIGHTS A light designed to illuminate a pool from beneath the water surface.
UNIVERSAL GRAVITATION CONSTANT The acceleration of a free falling body in the gravity field of the Earth. g = 32.2 feet/second/second
UPPER DISTRIBUTION SYSTEM Those devices designed to distribute the water entering a permanent medium filter in a manner so as to prevent movement or migration of the filter medium. This system shall also properly collect water during filter backwashing unless other means are provided.
[ V ]
VACUUM Negative pressure; a region in a pump or a pipe that is below atmospheric pressure.
VACUUM WALL FITTING The fitting in the wall of the pool just below the water level to which is attached the hose for the underwater suction cleaner.
VELOCITY The measurement of the motion of liquids, expressed in feet per second.
VENTURI A cylindrical tube that gradually increases in size. When used in conjunction with a nozzle, it converts the velocity of the liquid being pumped to pressure.
VENTURI TUBE A tube, which has a constricted throat, which causes differences in pressure and can be used to operate feeding devices, instruments and to measure flow.
VERTICAL WALL Shall refer to the wall up to a positive 11° angle towards the pool’s interior from plumb.
VIRUS The smallest infectious microorganism, made of RNA or DNA, in a protein shell, which grow only in other, living cells. They are 0.004 to 0.1 microns in size and about 100 times smaller than bacteria.
VISCOSITY The resistance of a fluid to flowing freely, caused by friction from its molecules.
VOC Volatile Organic Compound-a category of water contaminates.
VOLTAGE LOSS The amount of electricity used to force current(amps) to where it needs to go. This can be caused various ways such as too small of wire, too long of a run, etc.
VOLTS An electrical measurement of motor performance where voltage(volts) = current(amps) x resistance(ohms). Volts measures the pressure of electricity.
VOLUME The contents of a space that is formed by lines that can be measured in three directions (length x width x height). In pipe the formula is Area x Pipe Length.
VOLUTE CASE A pump housing that is spiral or scroll shaped where the suction and discharge pipes screw into the unit.
[ W ]
WADING AREA That area less than 3 feet in depth devoted to activity of non-swimmers.
WALL SLOPE The inclination from vertical in a pool wall, expressed in degrees or in feet (or inches) of horizontal distance in a given depth in feet (or inches).
WALLS The interior pool wall surfaces consisting of surfaces from the plumb to a 45° slope.
WATER HAMMER The shock wave or series of waves caused by the resistance of inertia to an abrupt change of water flow through a water piping system. Water hammer may produce an instantaneous pressure many times greater than the normal pressure. For this reason, many building codes now require the installation of a "water hammer arrestor" or accumulation device to absorb shock waves and prevent damage to appliances such as washing machines as well as water treatment components such as reverse osmosis membranes.
WATER LINE The water line shall be defined in one of the following ways:
WATER LINE - OVERFLOW SYSTEM The water line shall be at the top of the overflow rim.
WATER LINE - SKIMMER SYSTEM The water line shall be at the midpoint of the operating range of the skimmers.
WATER SOFTENER A pressurized water treatment device in which hard water is passed through a bed of cation exchange media for the purpose of exchanging calcium and magnesium ions for sodium or potassium ions, thus producing a "softened" water which is more desirable for laundering, bathing and dish washing. This cation exchange process was originally called zeolite water softening or the Permutit Process. Most modern water softeners use a sulfonated bead form of styrene/divinylbenzene (DVB) cation resin.
WATTS A measurement of electrical power where watts = volts x amps. One watt is the rate of energy expended when a steady current of one amp flows under a pressure of one volt. 1HP = 746 Watts.
WET NICHE A watertight and water cooled unit submerged and placed in a niche in the pool wall.
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# Note: These definitions are offered to assist the public in understanding some of most often used water terms. If you desire a legal definition, please contact a water attorney.
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