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The table below may help you identify which contaminants to test for in your drinking water. The table concentrates only on the contaminants that leave sensory clues - taste, deposits, smell, and color. Be aware that if some of these chemicals are present at low levels in the drinking water, they may not leave any noticeable signs. Even at low, unnoticeable levels, some of these chemicals can cause health problems. Even if specific contaminates can be identified by color, smell, or taste, only a laboratory test can tell you the quantity of contaminant actually present - or can verify that your identification was accurate. Testing should always be done by a reputable or certified laboratory. Several of the contaminants below, while not harmful themselves, may provide an indication that other harmful contaminants, not detectable by the senses, might be present as well. Consult others in your area who may have information on contaminants that are liable to be present in the local water.  Possible sources of information would be the Environmental Protection Agency (EPA), other environmental groups, local health officials, your water company, neighbors, pump/well companies, etc. Many of the contaminants in the list below that leave sensory clues are not harmful at all, or, at worst, may cause minor health problems even at fairly high levels.   Many more contaminants are are not detectable (without testing) and are harmful in extremely small quantities.  Even if your water looks, tastes, and smells great, there is no guarantee that harmful contaminants are not present. This chart is not meant to provide a definitive statement on what chemicals are actually in your water.  Only water tests by a reputable laboratory can identify specific contaminants and the levels of contamination.  The chart can only provide a guide to possible causes for some common drinking water problems based on very subjective interpretations of your water's observable characteristics.  Also, as mentioned above, even correct identification of contaminants based on sensory clues does not mean that there are not other harmful contaminants present that are not detectable by the senses. The notations indicating which treatment method removes which contaminant are as accurate as I could make them after reviewing many sources, but you will need to carefully double-check any decision you make regarding a treatment method with the manufacturer from which you plan to purchase the treatment unit to make certain that it is certified do what you expect it to do. Do not use this table exclusively to determine which contaminants to test for, since other, harmful, undetectable contaminants may be present.

Color of Water
Water Problem	Contaminant	Source of Contaminant	Health Effect(s)	Treatment(s)
Blue to Blue-green	Copper	Much of copper contamination comes from home plumbing and fixtures when the water is corrosive.  If you have copper contamination due to corrosion, you may also have lead in your water since the conditions responsible for leaching copper out of a pipe or fixture are the same as those that will leach lead, if present. lead does NOT leave sensory clues at dangerous levels!	Essential mineral Mostly a nuisance, although In fairly high doses copper can cause gastrointestinal problems.   More important as an indicator of possible lead contamination - consider having your water tested for lead.	Acid neutralization of whole house water to minimize corrosion. If contamination is from natural sources, use ion exchange for whole house (& possibly POU). Reverse osmosis and distillation are effective POU treatment methods
Cloudy, or Milky	Small air bubbles	Air dissolved in the water before or during pumping or treatment, may naturally be in well water.	Harmless	Bubbles will eventually rise to the surface and disappear
	Methane bubbles	Methane is odorless, so unless the water also contains odor-causing chemicals like hydrogen sulfide, methane will be difficult to identify.	Methane is extremely flammable or explosive if confined!	Bubbles will eventually rise to the surface and disappear For methane, aerate the water prior to use. The aerator must be vented to the open air to permit the gas to escape into the atmosphere.
	Very fine dirt or clay particles, or organic matter	Naturally, from soil,  rocks, and living things.	Normally just a nuisance.  However, Abnormal cloudiness can be an indication that filtration of more harmful invisible contaminants (like bacteria and cysts) has failed - test the water - locate & correct cause of the problem.	Cloudiness from these contaminants will not clear on standing like bubbles will. Treat with sediment filtration  unless there are pathogens in the water - then disinfect and filter.
Reddish - orange	Iron 1	Naturally, from soil & rocks, sometimes from galvanized pipes if water is corrosive.	Nuisance	Treatment methods listed below  1
Dark brown to Black	Manganese 1	Naturally, from soil & rocks	Nuisance	Treatment methods listed below  1
Yellow	Tannins (humic acid)	Naturally, from organic soil and vegetation	Nuisance - water may also have a bitter taste	Activated Carbon Filtration Up to 3.0 ppm: Absorption with an ion exchange resin greater than 3.0 ppm: Chlorination followed by filtering
Deposits, Spots, & Sediment
Water Problem	Contaminant	Source	Health Effect(s)	Treatment(s)
Soap scum and Bathtub rings. Also, failure of soap to lather well	Calcium and magnesium carbonate (Hard water)	Naturally, from soil & rocks	Essential mineral Nuisance in water over about 5 grains of hardness	Standard water softener ion exchange.
Scaly, whitish deposit on fixtures, plumbing lined with scale.	Calcium and magnesium carbonate (Hard water)	Naturally, from soil & rocks	Essential mineral Nuisance in water over about 5 grains of hardness	Standard water softener ion exchange. Clean deposits on the fixtures with a rag soaked in vinegar
Spots on clothing	Calcium and magnesium carbonate (Hard water)	Naturally, from soil & rocks	Essential mineral Nuisance in water over about 5 grains of hardness	Standard water softener  ion exchange.
Spots on dishes, glassware, and flatware	Calcium and magnesium carbonate (Hard water)	Naturally, from soil & rocks	Essential mineral Nuisance in water over about 5 grains of hardness	Standard water softener  ion exchange.
	High levels of Total Dissolved Solids (TDS) 2 (also hard water)	natural sources or from human contamination	Usually a nuisance. May be harmful, depending on the contaminant(s) present.  Use common sense and your home's location (for instance, do you live in an agricultural or industrial area, or next to a waste dump) to decide if testing is warranted.	TDS can be a mix of many chemicals. 2 Use whole house ion exchange and activated carbon to remove many contaminants. Reverse osmosis and distillation are effective POU treatment methods A solid block, activated carbon filter will reliably remove most of the organic TDS
Spotting, mottling,  or pitting of teeth	Fluoride	Naturally from soil & rocks Fluoride can also be added by water treatment companies.	At about 1 mg/l Fluoride helps prevent tooth decay.  Above about 3 - 4 mg/l Fluoride can cause staining of the tooth enamel and other problems.	Activated alumina filtration Reverse osmosis and distillation are effective POU treatment methods
Red - brown or black - brown slime in plumbing system	Iron or Manganese Bacteria	The bacteria feed on iron or manganese dissolved in the water	Nuisance - can clog plumbing and filters	Chlorine or permanganate treatment of well
Reddish - brown sediment. Typically clears after running the water for a few minutes	Iron	Dissolved iron precipitates when oxygen reaches it.  Sometimes the iron sediment in the distribution system  or home pipes is disturbed - when this happens, the water can get really "thick" with sediment for a while.	Nuisance	If the problem is caused by dissolved iron in your water, treat it with the methods listed below. 1 If the problem is caused by disturbed sediment from pipes, run the water for a while, and it should clear.  The sediment can be filtered as well.
Grittiness, abrasiveness of water, and sediments at the bottom of tubs and sinks	Fine sand, grit	Sand or very fine sediments that gets through the filtering screens in wells or resists the coagulation stage during water treatment.	Nuisance	Sedimentation or Sediment Filter
Staining
Water Problem	Contaminant	Source	Health Effect(s)	Treatment(s)
Blue-green stains on sink and porcelain fixtures	Copper or brass	Much of copper contamination comes from home plumbing and fixtures when the water is corrosive.  If you have copper contamination due to corrosion, you probably also have lead contamination	Essential mineral Mostly a nuisance, although In fairly high doses copper can cause gastrointestinal problems.   More important as an indicator of possible lead contamination	Acid neutralization of whole house water to minimize corrosion.   If contamination is from natural sources, use ion exchange for whole house (& possibly POU). Reverse osmosis and distillation are effective POU treatment methods
Brown-red stains, and discolored clothing	Iron	Naturally, from soil & rocks, sometimes from galvanized pipes if water is corrosive.	Mostly a Nuisance - Neurological effects at very high levels	Treatment methods listed below  1
Black stains on fixtures and laundry	Manganese	Naturally, from soil & rocks.	Mostly a Nuisance - Neurological effects at very high levels	Treatment methods listed below  1
Blackening and pitting of metal sinks and fixtures	Hydrogen sulfide (gas)	Naturally occurring, more common in wells than surface water. Usually present in water with high levels of iron and a low pH.	Promotes corrosion due to its activity as a weak acid. Also, its presence in the air causes silver to tarnish in a matter of seconds High hydrogen sulphide concentrations are both inflammable and poisonous. While such concentrations are rare, their presence in drinking water has been known to cause nausea, illness and in extreme cases, death.	Low to moderate concentrations - use oxidizing filter followed by carbon filter Aeration followed by filtration medium to high concentrations - use chlorination followed by activated carbon
Gray stains	Aluminum	The primary source of aluminum in drinking water is from the use of aluminum sulfate (alum) as a coagulant in water treatment plants.	Probably just a nusianc. Although there was some concern several years ago that aluminum contributed to Alzheimer's disease, research does not seem to have supported that idea.	Reverse osmosis or Distillation
Yellow stains on fabrics, china dishes and sinks, fixtures, etc.	Tannins (humic acid)	Naturally, from organic materials in soil and from vegetation	Nuisance - water may also have a bitter taste	Activated Carbon Filtration Up to 3.0 ppm: Absorption with an ion exchange resin greater than 3.0 ppm: Chlorination followed by filtering
Taste
Water Problem	Contaminant	Source	Health Effect(s)	Treatment(s)
Alkaline taste (bitter, "soda" taste)	Hydroxides, Carbonates and Bicarbonates High pH water Recommended pH levels 6.5 to 8.5	Bicarbonates are the most common sources of alkalinity.  Almost all natural supplies have a measurable amount of this ion.	Nuisance	pH correction using either a neutralizing filter or chemical feed pump to lower the pH - link
Metallic taste	Iron, manganese, copper, lead, or other metals	wide range of possible  sources, depending on metal	Nervous system disorders from lead, mercury, arsenic.  Possible cancer risk from nickel, arsenic, chromium.	Cation exchange for whole house treatment. Reverse osmosis, distillation, or specialized ion exchange resin for POU treatment
Salty, brackish taste and pitting of fixtures.	Sodium, chloride, sulfate, inorganic salts	Sodium salts are present to a greater or lesser degree in all natural waters.	Sodium can cause problems for people with hypertension. Sulfate can cause gastrointestinal problems.	Reverse osmosis, distillation, or specialized ion exchange resin for POU treatment
Sharp chemical taste or odor, or "oily" consistency	Pesticides or semi-volatile compounds	All are synthetic organic compounds. Contamination of water supply from storage tank leaks, agricultural applications,  dumping, improper disposal, etc.	Risk of cancer. Could affect any bodily organ system	If these contaminants are present in levels that can be easily tasted or smelled, immediately STOP using the water for drinking and cooking and drink bottled water - probably shouldn't bathe in it either - until the contaminant level goes down significantly. A high quality, solid block, activated carbon filter will remove undetectable, but dangerous, concentration of these chemicals that might be present even after public water treatment.
Odor
Water Problem	Contaminant	Source	Health Effect(s)	Treatment(s)
Chlorine smell (like bleach or swimming pool)	Chlorine,  Chloramines	Disinfection chemicals.  Some "residual disinfectant" must remain in the water during distribution to prevent reinfection of the water.	Chlorine does not appear to cause health problems at levels normally used for disinfection.   The possible health problems result from the formation of disinfection byproducts (DBPs) discussed elsewhere.	Activated Carbon Filtration for whole house reduction of chlorine A POU, high quality, solid block, activated carbon filter will remove chlorine and, more importantly, disinfection byproducts from drinking and cooking water. Distillation and RO will also remove these contaminants.
Detergent smell (foamy water)	Foaming agents, dilute sewage	Discharges from the septic system into sources of underground water supply;  Accidental presence of detergent in the water supply or wells If this occurs with municipal water, it could mean problems with the treatment system.	Risk of disease if bacteria are present. Could harm infants.	For wells, locate and eliminate source followed by strong dose of chlorine An activated charcoal filter absorbs small amounts of detergent
Sweet, perfume odor	Volatile (or semi-volatile) organic compounds like MTBE	All are synthetic organic compounds. Contamination of water supply is from storage tank leaks, dumping, improper disposal, etc. If these contaminants are present in levels that can be easily tasted or smelled, STOP using the water for drinking and cooking immediately and drink bottled water until the level is reduced.	Risk of cancer. Could affect kidney, liver, or central nervous system.	Find and remove source of contamination if it is from a single source, or find a new source of water. A high quality, solid block, activated carbon filter will remove undetectable, but dangerous, concentration of these chemicals that might be present even after public water treatment.
Smells like fish	Barium, Cadmium	Barium is a naturally occurring metal found primarily in the Midwest. Cadmium makes its way into the water supplies as a result of deterioration of galvanized plumbing, industrial waste or fertilizer contamination	Barium is highly toxic when its soluble salts are ingested	Standard water softener ion exchange. Reverse Osmosis Distillation
	Organic matter	Naturally occurring	Nuisance	Activated Carbon Filtration
	Chloramine	Traces of chlorine and ammonia compounds used for desinfection of wastewater.	Nuisance	Activated Carbon Filtration
Smells like rotten eggs	Hydrogen sulfide (gas)	Naturally occurring, more common in wells than surface water. Usually present in water with high levels of iron and a low pH.	Promotes corrosion due to its activity as a weak acid. Also, its presence in the air causes silver to tarnish in a matter of seconds High hydrogen sulphide concentrations are both inflammable and poisonous. While such concentrations are rare, their presence in drinking water has been known to cause nausea, illness and in extreme cases, death.	Low to moderate concentrations - use oxidizing filter followed by carbon filter Aeration followed by filtration medium to high concentrations - use chlorination followed by activated carbon
Oil or gas smell	Methane	Wells that contain methane are generally located in areas where gas and oil wells are common sights	Danger of fire or explosion	Aerate water prior to use. The aerator must be vented to the open air to permit the gas to escape into the atmosphere.
	Gasoline or semi-volatile organic compounds	All are distilled or synthetic organic compounds. Contamination of water supply is from storage tank leaks, dumping, improper disposal, etc. If these contaminants are present in levels that can be easily tasted or smelled, immediately STOP using the water for drinking and cooking and drink bottled water until the level is reduced.	Risk of cancer. Could affect kidney, liver, or central nervous system.	Find and remove source of contamination if it is from a single source, or find a new source of water. A high quality, solid block, activated carbon filter will remove undetectable, but dangerous, concentration of these chemicals that might be present even after public water treatment.
Smells like sewage	Selenium	The concentration found in drinking water is usually low, and comes from natural sources.	Essential mineral A nuisance if it effects water odor. Can be toxic at high levels of exposure	Ion exchange Reverse Osmosis Distillation
	Sewage	Leakage from a septic system, waste treatment plant, feed lot, farmyard, etc.	High probability of contamination with E. coli and other pathogens as well as nitrates.	If raw sewage is present in levels that can be easily smelled, immediately STOP using the water for drinking and cooking and drink bottled water until the problem has been identified and fixed.
Musty, earthy smell	Decaying Organic matter (leaves, algae)	Naturally occurring, usually in surface or shallow wells	Nuisance, usually	Activated carbon filtration for whole house treatment. Combine with sediment filter if particulates are present. RO, distillation, or Activated carbon filtration for POU treatment

Iron and Manganese - In wells where oxygen content is low, the water containing iron & manganese is clear and colorless because the iron and manganese are dissolved. Water from the tap may be clear at first, but when exposed to air, iron and manganese are oxidized and change from the colorless, dissolved forms to colored, solid forms. Iron precipitates as red-brown particles: the larger particles settle out of the water, but smaller particles may remain suspended and give the water a red tint.  Manganese forms a black precipitate or black tint to the water.
Iron and manganese can affect the flavor and color of food and water. They may react with tannins in coffee, tea, and some alcoholic beverages to produce a black sludge, which negatively affects both taste and appearance.
Iron will cause reddish-brown staining of laundry, porcelain, dishes, utensils and even glassware. Manganese acts in a similar way but causes a brownish-black stain. Soaps and detergents do not remove these stains, and use of chlorine bleach and alkaline builders (such as sodium and carbonate) may intensify the stains.
Iron precipitates can cause problems if they build up in pipelines, pressure tanks, water heaters or water softeners. 
A secondary problem that often results from dissolved iron or manganese in water is iron or manganese bacteria. These nonpathogenic (not health threatening) bacteria occur in soil, shallow aquifers and some surface waters. The bacteria feed on iron and manganese in water. These bacteria form red-brown (iron) or black-brown (manganese) slime in toilet tanks and can clog water systems.
Treatment methods for iron and manganese contamination are discussed in detail at the NebGuide listed below:
Whole House Treatments - the link below describes these techniques in detail.
(1) phosphate compounds;
(2) ion exchange water softeners;
(3) oxidizing filters;
(4) aeration (pressure type) followed by filtration; and
(5) chemical oxidation followed by filtration.
Point of Use Treatments
Since problems with iron and manganese are aesthetic and nuisances (affecting water throughout the house rather than health hazards), it makes more sense to use a whole house water treatment system if you have this problem.  Distillation and reverse osmosis will also remove these contaminants from water used for drinking and cooking.
The NebGuide, Drinking Water: Iron and Manganese, has a wealth of additional information about this problem.

TDS (Total Dissolved Solids) - TDS is a measure of all inorganic and organic substances dissolved in water. It is used to indicate an increase in one or more contaminants.  Natural or human-caused activity such as mining or drilling may disturb the water-bearing formation and cause more materials to dissolve in water.  Heavily salted roads, improperly lined landfills, junk yards, industrial activities, or chemical spills also may lead to increased TDS concentrations.  TDS values above 1,000 ppm indicate problems. Further testing usually is required to pinpoint the exact problem.  High TDS may result in offensive odors, tastes, colors and health problems depending on the specific contaminant(s) present.

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Copyright © 2005 Randy Johnson. All rights reserved.	Updated November 2011