AE-1045, June 1992
Tom Scherer, Extension Agricultural Engineer
Many people determine the quality of the water they consume by how it smells, tastes or looks. Although these are important criteria, they are primarily aesthetic properties of the water. A glass of water may not look, smell or taste good, but it could still be suitable to drink from a health standpoint.
The way water looks, smells and tastes can be used to help determine what type of treatment is necessary to improve the quality of the water. The following guidelines will help you determine if there are any problems with your water and what the most likely cause of those problems might be. All you need is a clear container to take a water sample and then use your senses of sight, smell and taste.
Water is clear when first drawn from the raw water tap then becomes yellow or reddish in appearance, but clears upon standing for 24 hours.
Dissolved iron present.Water is yellow or reddish when first drawn from the raw water tap but clears upon standing for 24 hours.
Undissolved iron present.Yellow or brownish cast to water even after softening and/or filtering and does not clear up after standing for 24 hours.
Tannin (humic acid) in water. Comes from water passing through coal veins, peaty soils and decaying vegetation.Black cast to water that clears upon standing for 24 hours.
Dissolved manganese present.Milky water.
Excessive air in the water caused by the well pump sucking air (excessive drawdown) or a malfunctioning pressure tank. Also, can be caused by high amounts of bicarbonate precipitates resulting from an increase in pH.Blackening, tarnishing, or pitting of metal sinks, utensils, pipes, etc.
High amounts of salt (chlorides and sulfates) or hydrogen sulfide gas.Green stains on sinks and other porcelain bathroom fixtures. Blue green cast to water.
Acidic water (pH below 6.8) reacting with brass and copper pipes and fittings.Suspended matter in water.
Caused by riled up water in a surface supply or sand pumping from a well.Soap curds and lime scum in wash basins and bathtubs. Whitish scale deposits in tea kettle and on the ends of plumbing fixtures (faucet, shower head, etc.).
Hard Water caused by calcium and magnesium salts in the raw water supply.Stained aluminum cookware.
High dissolved mineral content and high alkalinity in the raw water.
Chlorine smell.
Normal chlorination of public or private well sources.Fishy, musty or earthy smell.
Generally harmless organic matter. Commonly associated with surface water supplies.Rotten egg odor from the raw water tap or directly from the well.
Dissolved hydrogen sulfide gas in the raw water.Rotten egg odor only from the hot water tap.
Sulfates present in the raw water reacting with the magnesium anode which causes hydrogen sulfide gas. Can be corrected by removing the anode or replacing it with an aluminum anode.Detergent odor and water foams when drawn. Also septic odor.
Leakage from a sewer system is entering the water supply.
Salty flavor to the water that may have a laxative effect in some situations.
High salt content (primarily sodium sulfate and magnesium sulfate).Metallic taste.
High concentration of manganese, or possibly other metals.
When the cause of a water problem has been identified, then a method of treatment can be used to correct or minimize the problem. Before purchasing a treatment system, first have your water analyzed by a state certified laboratory to determine the quantity of foreign material in your water. The most common water tests are for:
After the water is analyzed, you can use the following chart to determine what treatment methods are needed to correct the problem. You may have identified more than one problem. If this is the case, you may need more than one type of treatment. Many reputable water treatment companies have equipment that will treat more than one problem.
------------------------------------------------------------ Raw Water Problem Common Treatment Method ------------------------------------------------------------ Bacterial contamination Treat using chlorination or other forms of disinfection (boiling, iodine, etc.) until the source of contamination is found and corrected or removed. Fine sand, clay Remove using mechanical (fine screen) or other sediments or sand filtration. Odor and taste other Corrected with activated carbon than ROTTEN EGG SMELL filters. Hydrogen Sulfide Gas Remove using chlorination followed by (ROTTEN EGG SMELL) sedimentation or use an oxidation filter (sometimes called an aeration filter) followed by an activated carbon filter to remove excess chlorine. Small amounts of Remove with a common water softener. dissolved iron and The water softener manufacturer should manganese. have a level of iron removal rating. Higher amounts of Remove using an oxidizing agent such as dissolved iron and potassium permanganate or chlorine manganese followed by a mechanical screen or use a green sand filter. Suspended iron and Remove using mechanical (fine screen) manganese particles or sand filtration. Hard water Treat using a water softener. Acid water Treat with a neutralizing filter (adds (pH less than 5.0) calcium carbonate) Alkaline water Treat by injecting a weak acid (acetic (pH greater than 9.0) acid or white vinegar) Tannin (humic acid) Remove using chlorination with a detention tank or a special anion exchange unit. Volatile organic1 Remove using an activated carbon compounds, certain filter. Other treatment options pesticides, trihalo- include reverse osmosis or distillation. methanes and radon Nitrates, heavy metals* Remove with reverse osmosis or by (lead, copper, etc.), distillation. Nitrates can be removed high total dissolved with an anion exchange unit. solids (TDS), sodium, sulfates. ------------------------------------------------------------ *These problems are not generally noticeable to human senses. Testing for these constituents should be performed by a trained professional familiar with the problems that can cause these forms of contamination.
A brief description of the six most common types of household water treatment is found on the following chart. The list explains the main use for the treatment method and also, equally important, the major limitations of the method.
------------------------------------------------------------------------
Treatment
Method Main Use Restrictions
------------------------------------------------------------------------
Water Reduces water hardness minerals Replaces calcium and
Softening (calcium and magnesium) by magnesium with sodium
replacing them with sodium. which can present a
problem for people on
Softened water requires less low sodium diets. A
soap or detergent for washing kitchen faucet should be
and cleaning. left unsoftened for
drinking purposes.
Reduces scale formation in Periodic backwashing and
pipes, water heaters and on regeneration of the
faucets. Improves sudsing resin bed using salt
ability of soaps and detergents. brine is required.
------------------------------------------------------------------------
Oxidative Reduces iron and manganese Periodic backwashing
Iron concentrations to levels where required. Periodic
Filtration they don't stain clothes or recharging with potassium
plumbing fixtures. permanganate is
required.
Prevents odors caused by
hydrogen sulfide Should be installed
(rotten egg smell). upstream from a water
softener.
------------------------------------------------------------------------
Activated Removes general taste and odor Generally does not
Carbon problems including chlorine. remove nitrates, sulfates,
Filtration bacteria or heavy metals.
Usually installed at the Periodic replacement of
point-of-use for drinking activated charcoal
and cooking. (usually in canisters)
is required forcontinuous
operation.
------------------------------------------------------------------------
Reverse Reduces heavy metals, most Does not remove all
Osmosis pesticides, and fluoride to organic chemicals such
acceptable levels. as chloroform. Does not
remove 100% of most
Used primarily for drinking chemicals.
and cooking. Uses large amounts of
water for flushing.
------------------------------------------------------------------------
Distillation Removal of dissolved minerals, Produces bland tasting
trace amounts of heavy metals water.
and many organic chemicals.
Requires significant
Used primarily for drinking energy, therefore small
and cooking. capacity units are used.
------------------------------------------------------------------------
Chlorination Disinfection of biologically Not recommended as a
contaminated water supplies, continuous practice for
"shock" treatment of wells and the control of bacteria
storage tanks. in private water wells.
A new, bacteria free
Aids in the removal of high source of water should be
levels of iron and manganese. found.
Additional treatment is
required to remove
residual chlorine and
chlorinated organics.
------------------------------------------------------------------------
NDSU Extension Service Water Treatment Series -
TREATMENT SYSTEMS FOR HOUSEHOLD WATER SUPPLIES:
Additional NDSU Extension Service Bulletins:
AE-1045, June 1992
NDSU Extension Service, North Dakota State University of Agriculture and Applied Science,
and U.S. Department of Agriculture cooperating. Sharon D. Anderson, Director, Fargo, North
Dakota. Distributed in furtherance of the Acts of Congress of May 8 and June 30, 1914. We offer our
programs and facilities to all persons regardless of race, color, national origin, religion, sex, handicap,
age, Vietnam era veterans status, or sexual orientation; and are an equal opportunity employer.
This publication will be made available in alternative formats for people with disabilities
upon request 701/231-7881.
North Dakota State University
NDSU Extension Service