WATER TERMS GLOSSARY
ACID
A substance which releases hydrogen ions when dissolved in water. Most acids
will dissolve the common metals, and will react with a base to form a
neutral salt and water.
ACTIVATED CARBON
A granular material usually produced by the roasting of cellulose base
substances, such as wood or coconut shells, in the absence of air. It has a
very porous structure and is used in water conditioning as an adsorbent for
organic matter and certain dissolved gases. Sometimes called "activated
charcoal."
ABSORBENT
A substance which has the capacity to adsorb.
ADSORPTION
The process in which matter adheres to the surface of an adsorbent.
ALKALINITY
The quantitative capacity of water or water solution to neutralize an acid.
It is usually measured by titration with a standard acid solution of
sulfuric acid, and expressed in terms of its calcium carbonate equivalent. A
moderate amount of Alkalinity in your water is desirable because it reduces
the effect of corrosion. The EPA has not set a level for Alkalinity, but a
level greater than 100 ppm is recommended.
ALUMINUM
Aluminum can be found as a natural forming mineral or as a by product of
water that is corrosive or aggressive. Aluminum in the water may cause a
discoloration or cloudy appearance. The EPA maximum contaminant level for
aluminum in water is 0.2 ppm.
ANION
A negatively charged ion in solution, such as bicarbonate, chloride, or
sulfate.
ANION EXCHANGE
An ion exchange process in which anions in solution are exchanged for other
anions from an ion exchanger. In demineralization, for example, bicarbonate,
chloride, and sulfate anions are removed from solution in exchange for a
chemically equivalent number of hydroxide anions from the anion exchange
resin.
AQUIFER
A layer or zone below the surface of the earth which is capable of yielding
a significant volume of water.
ATOM
The smallest particle of an element that can exist either alone or in
combination with similar particles of the same element or a different
element.
ATTRITION
The process in which solids are worn down or ground down by friction, often
between particles of the same material. Filter media and ion exchange
materials are subject to attrition during backwashing, regeneration, and
service.
BACKWASH
The process in which beds of filter or ion exchange media are subjected to
flow opposite to the service direction to loosen the bed and to flush
suspended matter (collected during the service run) to waste.
BACTERIA
Unicellular micro-organisms which typically reproduce by cell division.
Although usually classified as plants, bacteria contain no chlorophyll.
BASE
A substance which releases hydroxyl ions which when dissolved in water.
Bases react with acids to form a neutral salt and water.
BED
The ion exchange or filter media in a column or other tank or operational
vessel.
BED DEPTH
The height of the ion exchange or filter media in the vessel after
preparation for service.
BRINE
A strong solution of salts(s), such as the sodium chloride brine used in the
regeneration of ion exchange water softeners; also applied to the mixed
sodium, calcium, and magnesium chloride waste solution from regeneration.
CALCIUM
One of the principal elements making up the earth's crust; its compounds,
when dissolved, make the water hard. The presence of calcium in water is a
factor contributing to the formation of scale and insoluble soap curds which
are a means of clearly identifying hard water.
CALCIUM MAGNESIUM
Two of the principal elements making up the earth's crust; its compounds,
when dissolved, make the water hard. The presence of calcium and magnesium
in water is a factor contributing to the formation of scale and insoluble
soap curds which are a means of clearly identifying hard water.
CAPACITY
An expression of the quantity of an undesirable material which can be
removed by a water conditioner between servicing of the media (i.e.,
cleaning, regeneration or replacement), as determined under standard test
conditions. For ion exchange water softeners, the capacity is expressed in
grains of hardness removal between successive regeneration's and is related
to the pound of salt used in regeneration. For filters, the capacity may be
expressed in the length of time or total gallons delivered between
servicing.
CARBON DIOXIDE
A gas present in the atmosphere and formed by the decay of organic matter;
the gas in carbonated beverages; in water it forms carbonic acid.
CATION
An ion with a positive electrical charge, such as calcium, magnesium and
sodium.
CATION EXCHANGE
Ion exchange process in which cations in solution are exchanged for other
cations from an ion exchanger.
CAUSTIC
Any substance capable of burning or destroying animal flesh or tissue. The
term is usually applied to strong bases.
CAUSTIC SODA
The common name for sodium hydroxide.
CHELATE
To form a complex chemical compound in which an ion, usually metallic, is
bound into a stable ring structure.
CHELATING AGENT
A chemical compound sometimes fed to water to tie up undesirable metal ions,
keep them in solution, and eliminate or reduce the normal effects of the
ion.
CHLORIDE
Chloride is a natural forming mineral found in water. High levels of
chloride can impact taste and also be associated with corrosion or high
Sodium content. Water with excessive amounts of chloride can be very toxic
to most plants. The EPA maximum contaminant level for chloride is 250 ppm.
CHLORINE
A gas, C12, widely used in the disinfection of water and an oxidizing agent
for organic matter, iron, etc.
CHLORINE CONTENT
Chlorine is added to water as a disinfectant to kill harmful organisms or
bacteria. Even though Chlorine is used in providing safe drinking water,
when it is in excess, it is the most common cause of taste and odor
problems. Also when Chlorine is combined with ammonia as a disinfectant
called chloramines, a byproduct as Trihalomethanes are formed, which cause
cancer. The EPA does not have a level for Chlorine but a concentration of
0.1 to 0.2 ppm is recommended and a level of 1.0 or greater is considered
very high.
CHLORINE DEMAND
A measure of the amount of chlorine which will be consumed by organic matter
and other oxidizable substances in a water before a chlorine residual will
be found; the difference between the total chlorine fed and the chlorine
residual.
COAGULANT
A material, such as alum, which will form a gelatinous precipitate in water,
and cause the agglomeration of finely divided particles into larger
particles which can then be removed by settling and/or filtration.
COAGULANT AID
A material which is not a coagulant, but which improves the effectiveness of
a coagulant, often by forming larger or heavier particles, speeding the
reactions, or permitting reduced coagulant dosage.
COAGULATION
The process in which very small, finely divided solid particles, often
colloidal in nature, are agglomerated into larger particles.
COLLOID
Very finely divided solid particles which will not settle out of a solution;
intermediate between a true dissolved particle and a suspended solid which
will settle out of solution. The removal of colloidal particles usually
requires coagulation to form larger particles which may be removed by
sedimentation and/or filtration.
COMPENSATED HARDNESS
A calculated value based on the total hardness, the magnesium to calcium
ratio, and the sodium concentration of a water. It is used to correct for
the reductions in hardness removal capacity caused by these factors in
cation exchange water
CONDUCTANCE
A measure of the ability of a solution to carry electricity; the reciprocal
of the electrical resistance. The unit of conductance is the mho (reciprocal
ohm).
CONDUCTIVITY
The quality or power to carry electrical current; in water, the conductivity
is related to the concentration of ions capable of carrying electrical
current.
COPPER
Copper in water is a common problem in many households. Copper is present
due to the corrosion of plumbing materials from Acidic (low pH) or
Aggressive water (low TDS). Common problems associated with copper due
corrosion are leaks in the plumbing system or blue-green staining. High
copper content can also cause some health concerns by effecting the stomach
and intestines. The EPA has set a maximum contaminant level of 1.3 ppm.
CORROSION
The destructive disintegration of a metal by electrochemical means.
CYCLE
A series of events or steps which ultimately lead back to the starting
point, such as the exhaustion-regeneration cycle of an ion exchange system;
sometimes incorrectly used in reference to a single step of a complete
cycle.
DEIONIZATION
The removal of all ionized minerals and salts (both organic and inorganic)
from a solution by a two-phase ion exchange procedure. First, positively
charged ions are exchanged 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. The
term is often used interchangeably with demineralization.
DEMINERALIZATION
The removal of ionized inorganic minerals and salts (not organic materials)
from a solution by a two-phase ion exchange procedure; similar to
deionization, and the two terms are often used interchangeably.
D.I. OR DI
Abbreviation for deionization.
DIALYSIS
The separation of components of a solution by diffusion through a
semi-permeable membrane which is capable of passing certain ions or
molecules while rejecting others.
DIFFERENTIAL PRESSURE
The difference in pressures at two points in a water system; may be due to
differences in elevation, or to friction losses or pressure drops due to
resistance to flow in pipes, softeners, filters or other devices.
DISINFECTION
A process in which pathogenic (disease-producing) bacteria are killed; may
involve disinfecting agents such as chlorine, or physical processes such as
heating.
DISSOLVED SOLIDS
The weight of matter in true solution in a stated volume of water; includes
both inorganic and organic matter; usually determined by weighing the
residue after evaporation of the water at 105 or 1800C.
DISTILLATION
The process in which a liquid, such as water, is converted into its vapor
state by heating, and the vapor cooled and condensed to the liquid state and
collected; used to remove solids and other impurities from water; multiple
distillations are required for extreme purity.
EFFICIENCY
The ratio of output per unit input; the effectiveness of performance of a
system; in an ion exchange system, often expressed as the amount of
regenerant required to produce a unit of capacity, such as the pounds of
salt per kilograin of hardness removal.
ELECTRODIAYSIS
A process in which a direct current is applied to a cell to draw charged
ions through ion-selective semi-permeable membranes, thus removing the ions
from the solution.
ENDPOINT
The point at which a process is stopped because a predetermined value of a
measurable variable is reached; the endpoint of an ion exchange water
softener service run is the point at which the hardness of the softener
effluent increases to a predefined concentration, often 1.0 grain per
gallon; the endpoint of a filter service run may be the point at which the
pressure drop across the filter reaches a predetermined value; the endpoint
of a titration is the point at which the titrant produces predetermined
color change, pH value, or other measurable characteristic.
EQUIVALENT PER MILLION
A unit of concentration used in chemical calculations, calculated by
dividing the concentration in ppm or mg/1 by the equivalent weight.
EXHAUSTION
The state of an ion exchange material in which it is no longer capable of
effective functioning due to the depletion of the initial supply of
exchangeable ions; the exhaustion point may be defined in terms of a
limiting concentration of matter in the effluent, or in the case of
demineralization, in terms of electrical conductivity.
FILTER
Specifically, a device or system for the removal of solid particles
(suspended solids); in general, includes mechanical, adsorptive, oxidizing
and neutralizing filters.
FLOCCULATION
The agglomeration of finely divided suspended solids into larger, usually
gelatinous, particles; the development of a "floc" after treatment with a
coagulant by gentle stirring or mixing.
FLOW CONTROL
A device designed to limit the flow of water or regenerant to a
predetermined value over a broad range of inlet water pressures.
FLUORIDATION
The quantity of water or regenerant which passes a given point in a
specified unit of time, often expressed in gallons per minute.
FLUORIDE
Fluoride can be found in water as natural mineral or as an additive to
public or municipal supplies. Fluoride can cause a discoloration or teeth
known as Fluorosis when in excessive levels in water. The EPA maximum
contaminant level for Fluoride in water is 2.0 ppm.
FLUSH TANK
A tank or chamber in which water is stored for rapid release to flush a
toilet or water closet.
FLUSH VALVE
A self-closing valve designed to release a large volume of water when
tripped, to flush a toilet or water closet.
FOULING
The process in which undesirable foreign matter accumulates in a bed of
filter media or ion exchanger, clogging pores and coating surfaces, thus
inhibiting or retarding the proper operation of the bed.
FREE AVAILABLE CHLORINE
The concentration of residual chlorine present as dissolved gas,
hypochlorous avid or hypochlorite, not combined with ammonia or in other
less readily available forms.
FREEBOARD
The vertical distance between a bed of filter media or ion exchange material
and the overflow or collector for backwash water; the height above the bed
of granular media available for bed expansion during backwashing; may be
expressed either as a linear distance or a percentage of bed depth.
GPG
Abbreviation for grains per gallon.
GRAIN
(gr.) A unit of weight equal to 1/7000th of a pound, or 0.0648 gram.
GRAIN PER GALLON
(gpg) A common basis for reporting water analyses in the United States and
Canada; one grain per U.S. gallon equals 17.12 milligrams per liter (mg/1)
or parts per million (ppm). One grain per British (Imperial) gallon equals
14.3 milligrams per liter or parts per million.
GRAM
(g) The basic unit of weight (mass) of the metric system, originally
intended to be the weight of one cubic centimeter of water at 4oC.
GREENSAND
A natural mineral, primarily composed of complex silicates, which possesses
ion exchange properties.
HARDNESS
A characteristic of natural water due to the presence of dissolved calcium
and magnesium; water hardness is responsible for most scale formation in
pipes and water heaters and forms insoluble "curd" when it reacts with
soaps. Hardness is usually expressed in grains per gallon, parts per
million, or milligrams per liter, all as calcium carbonate equivalent.
HARDNESS CONTENT
Hardness is a measurement of naturally occurring dissolved minerals Calcium
and Magnesium, hard water can inhibit the sudsing of detergents and soaps.
Hard water can scale pipes and decrease the life of appliances such as
washing machines, dishwashers, coffee makers. Hardness can also cause
spotting of fixtures, tiles, dishes, or glassware. The EPA has not set a
limit for hardness, but if your hardness is greater than 7 grains per gallon
(gpg) then you should consider installing a water softener.
HARDNESS LEAKAGE
The presence of a consistent concentration of hardness in the effluent from
an ion exchange water softener, often due to high concentrations of hardness
or sodium in the water being treated (see Leakage).
HARD WATER
Water with a total hardness of one grain per gallon or more, as calcium
carbonate equivalent.
HEAD
A measure of the pressure at a point tin a water system: expressed in pounds
per square or in the height of a column of water which would produce the
pressure.
HYDROLOGIC CYCLE
The water cycle, including precipitation of water from the atmosphere as
rain or snow flow of water over or through the earth, and evaporation or
transpiration to water vapor in the atmosphere. (see Transpiration).
HYPOCHLORITE
The "OC1" anion; calcium and sodium hypochlorites are commonly used as
bleaches and disinfecting agents.
ION
An atom or group of atoms which functions as a unit, and has a positive or
negative electrical charge, due to the gain or loss of one or more
electrons. (see Ionization).
ION EXCHANGE
A reversible process in which ions are released from an insoluble permanent
material in exchange for other ions in a surrounding solution; the direction
of the exchange depends upon the affinities of the ion exchanger for the ion
present, and the concentrations of the ions in the solution. (see Base
Exchange).
ION EXCHANGER
A permanent, insoluble material which contains ions that will exchange
reversibly with other ions in a surrounding solution. Both cation and anion
exchangers are used in water conditioning.
IONIZATION
The process in which atoms gain or lose electrons and thus become ions with
positive or negative charges; sometimes used as a synonym for dissociation,
the separation of molecules into charged ion in solution.
IRON
An element often found discolored in ground water (in the form of ferrous
iron) in concentrations usually ranging from zero to 10 ppm (mg/1). It is
objectionable in water supplies because it can effect water taste and cause
unsightly colors produced when iron reacts with tannins in beverages such as
coffee and tea. Iron causes staining after oxidation and precipitation, as
ferric hydroxide (yellow, brown, and red on clothing, dishes, fixtures, and
bathroom tile). Iron can also be found in a bacterial form which will appear
as black or brown slime and can effect the odor of your water. Iron is a
common water problem throughout the United States, it can be found in well
water and municipal water. The EPA has set a maximum level for Iron of 0.3
ppm in water, iron concentrations at this level or higher can cause
staining.
IRON BACTERIA
Organisms which are capable of utilizing ferrous iron (either from the water
or from steel pipe) in their metabolism and precipitating both ferric
hydroxide in their sheaths and gelatinous deposits. These organisms tend to
collect in pipe lines and tanks during periods of low flow, and to break
loose in slugs of turbid water to create staining, taste, and odor problems.
KILO:
A prefix used to indicate 1000 of the succeeding unit. (Kilo is also
sometimes used as an abbreviation for kilogram.)
KILOGRAIN (Kgr)
One thousand grains.
KILOGRAM (Kg)
One thousand grams.
LANGELIER'S INDEX
A calculated number used to predict whether or not a water will precipitate,
be in equilibrium with, or dissolve calcium carbonate. It is sometimes
erroneously assumed that any water which tends to dissolve calcium carbonate
is automatically corrosive.
LEAD
Lead in drinking water is a common problem, it comes from lead pipes,
solder, and brass fittings. Water that has a low pH or Total Dissolved
Solids will provide corrosive properties that can leach from your plumbing
system. Lead can cause learning and physical disabilities in children and
also Hypertension in adults. The EPA action level for Lead is 0.015 ppm.
LEAKAGE
The amount of contaminant or hardness remaining in water after filtering or
other treatment.
LIME
The common name for calcium oxide (Ca); hydrated lime is calcium hydroxide
[Ca(OH)2].
LIME SCALE
Hard water scale containing a high percentage of calcium carbonate.
LIMESTONE
A sedimentary rock, largely calcium carbonate, usually also containing
significant amounts of magnesium carbonate.
LITER
The basic metric unit of volume; 3.785 liters equals one U.S. gallon. One
liter of water weighs 1000 grams.
MAGNESIUM
One of the elements making up the earth's crust. Magnesium compounds, when
dissolved in water, make the water hard. The presence of magnesium in water
is a factor contributing to the formation of scale and insoluble soap curds.
MANGANESE
An element sometimes found in ground water, usually with dissolved iron but
in lower concentrations. Manganese is a typical natural occurring mineral
found in municipal and well water. Manganese effects the taste and the color
or water. Manganese can also cause staining of clothes and dishware and
black stains and other problems similar to iron. The EPA has determined that
concentrations greater than 0.05 ppm can cause these asethic problems.
MANGANESE GREENSAND
Greensand which has been processed to incorporate in its pores and on its
surface the higher oxides of manganese. The product has a mild oxidizing
power, and is often used in the oxidation and precipitation of iron,
manganese and/or hydrogen sulfide, and in their removal from water.
MEDIA
The selected materials in a filter that form the barrier to the passage of
certain suspended solids or dissolved molecules.
MEDIUM
Singular form of media.
MG/L
The abbreviation for milligrams per liter.
MICRON
A linear measure equal to one millionth of a meter.
MICRON RATING
The term applied to a filter to indicate the particle size of suspended
solids that will be removed. As used in industry standards, this is an
"absolute" not nominal rating.
MILLIGRAM PER LITER (mg/l)
A unit
concentration of matter used in reporting the results of water and waste
water analyses. In diluted water solutions it is practically equal to the
part per million, but varies from he ppm in concentrated solution such as
brine. As most analyses are performed on measured volumes of water the mg/l
is a more accurate expression of the concentration, and is the preferred
unit of measure.
MINERAL
A term applied to inorganic substances (such as rocks and similar matter)
found in the earth strata, as opposed to organic substances such as plant
and animal matter. Minerals normally have definite chemical composition and
crystal structure. The term is also applied to matter derived from minerals,
such as the inorganic ions found in water. The term has been incorrectly
applied to ion exchangers, even though most of the modern materials are
organic ion exchange resins.
MOLECULE
The simplest combination of atoms that will form a specific chemical
compound; the smallest particle of a substance which will still retain the
essential composition and properties of that substance, and which can be
broken down only into atoms and simpler substances.
MOST PROBABLE NUMBER (MPN)
The term used to indicate the number of organisms which, according to
statistical theory, would be most likely to produce the results observed in
certain bacteriological tests; usually expressed as a number in 100 ml of
water.
NEGATIVE CHARGE
The electrical charge on an electrode or ion in solution due to the presence
of an excess of electrons.
NEUTRAL
In electrical systems, the term used to indicate neither an excess nor a
lack of electrons; a condition of balance between positive and negative
charges. In chemistry, the term used to indicate a balance between acids and
bases; the neutral point on the pH scale is 7.0, indicating the presence of
equal numbers of free hydrogen (acidic) and hydroxide (basic) ions.
NEUTRALIZATION
In general, the addition of either and acid or a base to a solution as
required to produce a neutral solution. The use of alkaline or basic
materials to neutralize the acidity of some waters is a common proactive in
water conditioning.
NITRATE NITROGEN
Nitrates are commonly found in well water from agricultural areas. It comes
from fertilizers, industrial wastes, septic systems, and animal wastes. High
amounts of nitrate effect the bloods ability to carry oxygen. Most
susceptible are infants where nitrate poisoning can cause death by a health
diagnosis known as "The Blue Baby Syndrome." The EPA has a set maximum
contaminant level of 10 ppm for Nitrate Nitrogen.
NONCARBONATE HARDNESS
Water hardness due to the presence of compounds such as calcium and
magnesium chlorides, sulfates or nitrates; the excess of total hardness over
total alkalinity.
OPERATING PRESSURE
The range of pressure, usually expressed in pounds per square inch, over
which a water conditioning device or water system is designed to function.
OSMOSIS
A process of diffusion of a solvent (such as water ) through a
semi-permeable membrane which will transmit the solvent but impede most
dissolved substances. The normal flow of solvent is from the dilute solution
to the concentrated solution.
OXIDATION
A chemical process in which electrons are removed from an atom, ion or
compound. The addition of oxygen is a specific form of oxidation. Combustion
is an extremely rapid form of oxidation, while the rusting of iron is a slow
form.
PARTICLE SIZE
As used in industry standards, the size of a particle suspended in water as
determined by its smallest dimension, usually expressed in microns.
PARTS PER MILLION (ppm)
A common basis for reporting the results of water and waste water analyses,
indicating the number of parts by weight of a dissolved or suspended
constituent, per million parts by weight or water or other solvent. In
dilute water solutions, one part per million is practically equal to one
milligram per liter, which is the preferred unit.
PATHOGEN
An organism which may cause disease.
PERMANENT HARDNESS
Water hardness due to the presence of the chlorides and sulfates of calcium
and magnesium, which will not be precipitated by boiling. This term is
largely replaced by "noncarbonate hardness."
pH
The reciprocal of the logarithm of the hydrogen ion concentration. The pH
scale is from zero to 14, and 7.0 is the neutral point, indicating the
presence of equal concentrations of free hydrogen and hydroxide ions. pH
values below 7.0 indicate increasing acidity, and pH values above 7.0
indicate increasing base concentrations.
PORTABLE EXCHANGE
A term applied to water softeners and filters which are designed for
connection to a water system with special fittings, and disconnection and
transport to a central station or plant for regeneration or servicing.
POSITIVE CHARGE
The electrical charge on an electrode or ion in solution due to the removal
of electrons.
PPM
The abbreviation for part per million.
PRECIPITATE
To cause a dissolved substance to form a solid particle which can be removed
by settling or filtering, such as in the removal of dissolved iron by
oxidation, precipitation, and filtration. The term is also used to refer to
the solid formed, and to the condensation of water in the atmosphere to form
rain or snow.
RATED CAPACITY
The basis for calculating the number of gallons delivered by a water
softener between regeneration's, or amount of time between servicing of a
filter, as determined under specific test conditions.
RATED SERVICE FLOW
The manufacturer's specified maximum flow rate at which a water softener
will deliver soft water, or a filter will deliver quality water (as
specified for its type) as determined under standard test conditions. A
manufacturer may also specify a minimum flow rate or a range of service
flows.
RATED SOFTENER CAPACITY
A water softener capacity rating based on grains of hardness removed while
producing soft water between successive regeneration's, and related to the
pounds of salt required for each regeneration as determined under standard
test conditions.
RAW WATER
Untreated water, or any water before it reaches a specific water treatment
device or process.
RED WATER
Water which has a reddish or brownish appearance due to the presence of
precipitated iron and/or iron bacteria.
REGENERANT
A solution of chemical compound used to restore the capacity of an ion
exchange system. Sodium chloride brine is used as a regenerate for ion
exchange water softeners; acids and bases are used as regenerants for the
cation and anion resins used in demineralization.
REGENERATION
In general, includes the backwash, brine, and fresh water rinse steps
necessary to prepare a water softener exchange bed for service after
exhaustion. Specifically, the term may be applied to the "brine" step in
which the sodium chloride solution is passed through the exchanger bed. The
term may also be used for similar operations relating to demineralizers and
certain filters.
REGENERATION LEVEL
The quantity of regenerant used in regeneration of an ion exchange unit or
system, usually expressed in pounds per regeneration and/or pounds per
regeneration per cubic foot of ion exchange.
RESIDUAL
The amount of a specific material remaining in the water following a water
treatment process. May refer to material remaining as a result of incomplete
removal (see Leakage) or to material meant to remain in the treated water
(see Residual Chlorine).
RESIDUAL CHLORINE
The amount of chlorine found in the water after treatment.
RESIN
Synthetic organic ion exchange material, such as the high capacity cation
exchange resin widely used in water softeners.
REVERSE DEIONIZATION
The use of the anion exchange resin ahead of the cation exchange resin (the
reverse of the usual order ) in a deionization system.
REVERSE OSMOSIS
A process for the removal of dissolved ions from water, in which pressure is
used to force the water through a semi-permeable membrane, which will
transmit the water by reject most other dissolved materials.
SALINE WATER
Water containing an excessive amount of dissolved salts, usually over 10,000
mg/1.
SALT
The common name for the specific chemical compound sodium chloride, used in
the regeneration of ion exchange water softeners. In chemistry, the term is
applied to a class of chemical compounds which can be formed by the
neutralization of an acid with a base.
SEQUESTER
A chemical reaction in which certain ions are bound into a stable, water
soluble compound, thus preventing undesirable action by the ions.
SEQUESTERING AGENT
A chemical compound sometimes fed into water to tie up undesirable ions,
keep them in solution, and eliminate or reduce the normal effects of the
ions. For example, polyphosphates can sequester hardness and prevent
reactions with soap.
SILICA
Silica can be found in water as a natural forming mineral or an additive to
public water supplies. Silica is not regulated by the EPA and does not cause
any health concerns. However, silica can cause spotting of glassware,
fixtures, and automobiles during the cleaning process.
SOAP
One of a class of chemical compounds which possesses cleaning properties,
formed by the reaction of a fatty acid with a base or alkali. Sodium and
potassium soaps are soluble and useful, but can be converted to insoluble
calcium and magnesium soaps (curd) by the presence of these hardness ions in
water.
SODA ASH
The common name for sodium carbonate, a chemical compound used as an
alkaline builder in come soap and detergent formulations; to neutralize acid
water,; and in the lime-soda ash water treatment process.
SODIUM
An ion found in natural water supplies, and introduced to water in the ion
exchange water softening process. Sodium compounds are highly soluble, and
do not react with soaps or detergents. The effects of Sodium are not clearly
understood. A high sodium intake can effect your blood pressure and cause
stress. The EPA has set a maximum contaminant level of 20 ppm for people who
have a sodium restricted diet.
SODIUM CHLORIDE
The chemical name for common salt, widely used in the regeneration of ion
exchange water softeners.
SOFT WATER
Any water which contains less than 1.0 fpf (17/1 mg/1) of hardness minerals,
expressed as calcium carbonate.
SOFTENED WATER
Any water that is treated to reduce hardness minerals to 1.0 gpg (17/1 mg/1)
or less, expressed as calcium carbonate.
SOLUTE
The substance which is dissolved in a solvent. Dissolved solids, such as the
minerals found in water, are solutes.
SOLVENT
The liquid, such as water, in which other materials (solutes ) are
dissolved.
SPECIFIC GRAVITY
The ratio of the weight of a specific volume of a substance to the weight of
the same volume of pure water at 4 C.
SULFATE
Sulfate is a natural forming mineral found in water. Sulfate effects the
taste of water, and when combined with bacteria or heated (water heater) may
effect the odor. High levels of Sulfate may impact the digestion system
causing a laxative effect. The EPA maximum contaminant level for sulfate in
water is 250 ppm.
SULFATE-REDUCING BACTERIA
A group of bacteria which are capable of reducing sulfates in water to
hydrogen sulfide gas, thus producing obnoxious tastes and odors. These
bacteria have no sanitary significance, and are classed as nuisance
organisms.
SULFUR
A yellowish solid element. The term is also used as a slang expression to
refer to water containing hydrogen sulfide gas.
TANNIN
Tannin is a common natural occurrence in well water. Tannin is produced by
decaying vegetation in the well system. It causes the water to have a yellow
of light brown color and can provide a bitter taste. There is currently no
EPA regulatory level for tannin in water.
TDS
The abbreviation for total dissolved solids.
THRESHOLD
A very low concentration of a substance in water. The term is sometimes used
to indicate the concentration which can just be detected.
TITRATION
An analytical process in which a standard solution in a calibrated vessel is
added to a measured volume of sample until an endpoint, such as a color
change, is reached. From the volume of the sample and the volume of standard
solution used, the concentration of a specific material may be calculated.
TOTAL ACIDITY
The total of all forms of acidity, including mineral acidity, carbon
dioxide, and acid salts. Total acidity is usually determined by titration
with a standard base solution to the phenolphthalein endpoint (pH 8.3).
TOTAL ALKALINITY
The alkalinity of a water as determined by titration with standard acid
solution to the methyl orange endpoint (pH approximately 4.5); sometimes
abbreviated as "M alkalinity." Total alkalinity includes many alkalinity
components, such as hydroxides, carbonates, and bicarbonates.
TOTAL DISSOLVED SOLIDS
(TDS)
The weight of solids per unit volume of water which are in true solution;
usually determined by the evaporation of a measured volume of filtered water
and determination of the residue weight. Total Dissolved Solids is a
measurement of any minerals or salts in the water. Bicarbonate, Chloride,
Sulfate, Calcium, Magnesium, Sodium are the major components of dissolved
solids in water. High amounts of these salts provide the major cause of
water taste problems. High TDS can cause the water to appear inappropriate
to drink, and spotting of glassware, fixtures, or painted surfaces such as
automobiles. Also high dissolved solids can diminish the life of home
appliances. The EPA has set a maximum contaminant level of 500 ppm.
TOTAL HARDNESS
The sum of all hardness constituents in a water, expressed as the equivalent
concentration of calcium carbonate. Primarily due to calcium and magnesium
in solution, but may include small amounts of metals such as iron which can
act like calcium and magnesium in certain reactions.
TOTAL SOLIDS
The weight of all solids ( dissolved and suspended, organic and inorganic)
per unit volume of water; usually determined by the evaporation of a
measured volume of water at 105 C in a pre-weighed dish.
TURBIDITY
A measure of the amount of finely divided suspended matter in water, which
causes the scattering and adsorption of light rays.
ZINC
Zinc is a product of a corrosive or aggressive water that is in contact with
a galvanized plumbing system. Zinc can effect the taste and color of the
water. The EPA maximum contaminant level for zinc is 5.0 ppm.
