Basement well (C) Daniel FriedmanGeneral Classes of Water Contaminants for Comprehensive Water Testing

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Testing for unknown water contaminants:

This article describes the types of contaminants that may be found in wells or drinking water and suggests a strategic approach to reduce the chances that you order a costly test that simply doesn't check for a local water contaminant that may be or is present in the water source. This article explains the general classes of water contaminants covered in a general water test.

We also provide a MASTER INDEX to this topic, or you can try the page top or bottom SEARCH BOX as a quick way to find information you need.

What drinking water contamination tests should you order? This article outlines the general classes or groups of comprehensive water tests that one would consider when attempting to perform comprehensive water testing for a broad range of contaminants.

General Classes of Water Contaminants Found in Drinking Water or Water Wells

Cross section of a drilled well and its equipment (C) InspectApediaCategories of water pollution contaminants by contaminant type

Categories of water contaminants by contaminant type: "Animal, mineral or vegetable" so to speak, include the twelve groups below. Some of these groups are overlapping, but I include them here as an easily-recognied digest of various government and private lists of water contaminants.

  1. Bacterial contaminants, including coliform from sewage contaminants or other bacteriological water contaminants that occur in the water source or well =(BACTERIA TEST GUIDE).

    This category also includes bacterial contaminants that may develop in building water equipment, tanks, or pipes (Legionella BACTERIA in WATER HEATERS)
  2. Bulk organic contaminants in water include hydrocarbons such as oil or grease*
  3. Other biological contaminants (other than bacterial) such as fungal or viral contaminants, and including more obvious biological contaminant sources such as a dead animal in a well or fecal waste from spiders or other insects that may enter a well.
  4. Chemical contaminants such as pesticides, herbicides, and in some cases contaminants that may be harmful though present only at very low levels, even below current permitted levels in drinking water, such
    as ENDOCRINE DISRUPTERS at BUILDINGS. See Halogenated hydrocarbons polycyclic aromatic hydrocarbons listed separately in that article series.

    Mercury contamination in water may be described under this chemical category or under that of metal contaminants. Similarly, many sources include nitrogen compounds in water among chemical contaminants.

    See CHEMICAL CONTAMINANTS in WATER for details about this category of pollutants.
  5. Gases, including radon in water wells, methane (potentyially explosive, METHANE GAS SOURCES ), and other gases such as sulphur or other odors (WATER ODORS, CAUSE CURE ). Note that bactrial or other water organic contaminants can also lead to water odors.
  6. Halogenated Hydrocarbons or Persistent Organics, a group of chemicals that are very resistant to decay such as DDT and PCBs.* - U.S. EPA (2014)
  7. Metal contaminants in water. The U.S. EPA cites metals such as iron, manganese, lead (LEAD IN DRINKING WATER), cadmium, zinc, and mercury, and metalloids such as arsenic and selenium* - U.S. EPA (2014)
  8. Nutrient contaminants in water, principally phosphorous nitrogen. The U.S. EPA notes ... nitrogen compounds such as ammonia. Elevated levels of phosphorous can promote the unwanted growth of algae. This can lead to the amount of oxygen in the water being lowered when the algae die and decay. High concentrations of ammonia can be toxic to benthic organisms.* - U.S. EPA (2014)
  9. Physical contaminants in water, in a category intended to describe refuse (plastic bottles, cans, trash or large particles, may be listed as category separate from "solid contaminants" described below.
  10. Polycyclic Aromatic Hydrocarbons (PAHs), a group of organic chemicals that includes several petroleum products and byproducts* - U.S. EPA (2014)
  11. Radioactive contaminants in drinking water such as radon (RADON IN WATER) are properly listed under chemical pollutants or gaseous pollutants.
  12. Solid contaminants in water such as sediment (soil, organic debris)

* The five asterisked contaminants in our longer list above are listed by the U.S. EPA as the "Five major types of pollutants are found in sediments" that might also be present in drinking water.

Seven Types of Water Pollution

In the U.K.,, a separate organization, lists the following more generalized types of water pollution. This list is helpful for understanding certain common properties held by various water pollutants. But this list is a bit confusing too as it mixes areas where water is found (surface water vs ground water) with types of pollution (microbiological and nutrient pollution).

Comprehensive tests for water pollutants

Watch out: a "water potability test" may sound like such testing tells you if water is completely safe to drink. But as the term "potability test" is commonly used, it refers only to a test for the presence or absence of coliform bacteria. While potability tests are inexpensive and are a very good way to start checking on the safety of drinking water, potability testing is no proof against other possible water contaminants including other forms of bacteria and various chemicals.

Comprehensive water testing covering the groups listed below may be appropriate when purchasing a new property, when local environmental conditions are unknown but suspect, or when building occupants have unusual health vulnerability or compromised immune systems.

We advise also that you speak with the local health department and neighbors to ask if there are any known specific issues or contaminants nearby, as we have by this means discovered very unusual local water contaminants which otherwise no one would have thought to test.

Be sure to review actual parameters with your home inspector or laboratory: parameters and costs vary.

Watch out: because the number of individual water contaminating substances is potentially very large, you risk both wasting money and falsely presuming that your drinking water is safe if you simply choose a "catchall" water test for contaminants. See Sampling Guidance for Unknown Contaminants in Drinking Water (cited below) for the U.S. EPA's comments on this problem.

Therefore we suggest as a general approach choosing water tests for unknown contaminants using a strategy that includes the steps listed below. To avoid an inefficient use of your water testing dollars, an approach that either raises questions for further investigation or closes off certain lines of investigation can be particularly helpful. For example if the property was a farm you might test for fertilizers. If the property was previously an orchard you might test for certain pesticides used in those businesses.

Comprehensive water testing covering the groups listed below may be appropriate when purchasing a new property, when local environmental conditions are unknown but suspect, or when building occupants have unusual health vulnerability or compromised immune systems.

Water is the universal solvent and it has the capabilities of dissolving just about anything. Because of this unique property water can easily become contaminated. Most common complaints are usually odor or staining problems; like those associated with sulfur and iron. However, serious contaminates as Lead and E.Coli Bacteria may be toxic affecting your family's health. This is why testing your water initially and annual monitoring is important.


Comprehensive Test would be expected to address four categories of testing in water:

1. Inorganic (this includes minerals and physical properties)

2. Organic (petroleum products, gasoline, fuel oils and solvents)

3. Microbiology (Coliform and other bacteria)

4. Radiological (radon gas)

This is a good way to start. The comprehensive Test is a powerful tool in detecting contaminates commonly found in surface and deep well waters. If there is a suspicion of Pesticides or Herbicides used near the water source it may be wise to include Pesticides and Herbicides analysis along with the Comprehensive Test.


After the initial water test, it is customary to monitor the quality to make sure that no changes have occurred. Utilizing the Standard Test yearly is a good way to monitor the water source. If on the original water test, Organic compounds or high amounts of Radon Gas were found, we would strongly suggest again testing with the Comprehensive Test.

General vs Comprehensive water test parameters

GENERAL WATER TEST PARAMETERS lists a set of general water test parameters for property buyers or owners who want to be more thorough than performing only a simple "coliform" or "bacteria" test (all that most banks require) but who do not have reason to test for more specific water contaminants.

One might take this approach after obtaining knowledge of property history, site inspection, conversation with neighbors, or check with a local health department. This test is more thorough than a simple coliform test but may not meet VA or FHA minimum standards for drinking water. Be sure to review actual parameters with your home inspector or laboratory: parameters and costs vary.

COMPREHENSIVE WATER TEST lists the parameters in a more comprehensive water test for common contaminants.

Question: causes of cloudy water

(May 14, 2016) Jeff said:
I replaced my regulator,and added some air in tank,my regulator is a 20,40 but I'm having problems with dirty,cloudy looking water,was cleared up for couple weeks but now looking dirty again.what do I do,I don't think I have my regulator adjusted right for 1 thing another I might off blower to much air in tank,looks like a 25 gallon tank.can you help me?

Reply: air, debris, bacteria, minerals, bad water softener


The pressure regulator settings won't be the cause of dirty water in the system, though debris in the water supply can clog the sensor port on the pressure control switch and ultimately cause it to malfunction.

First do this simple test: from your kitchen sink, fill a clear water pitcher with water. If the water looks cloudy set the pitcher on the countertop and watch it for a few minutes. If the cloudiness begins to clear up, usually from the bottom of the pitcher and then moving towards the top, you are seeing fine air bubbles entrained in the water, not a chemical or mineral contaminant.

If the cloudiness does not dissipate there may be a mineral, bacterial, or other contaminant in the water supply or a bacterial contamination in the water pressure tank and piping or in the water heater tank.

Check the incoming water supply for debris; you may need to add a filter or treatment system; another cause of dirty water can be a change in the water table or damage to (and leaks into) the well casing.

If you suspect a water tank, you'll need to clean, drain, disinfiect, sanitize the tank. Search for SANITIZSE a WATER SOFTENER for a nice procedure. Also search for WELL SHOCK PROCEDURE.


References & Research on general classes of contaminants found in drinking water

This website describes the types of water testing available, outlines common water test fees, describes the details of what parameters are included in various water test options, and gives advice to assist you in deciding what tests to order.


Continue reading at WELL WATER CONTAMINATION: CAUSES, CURES or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.




Watch out: Readers should also see our longer article WATER TESTING ADVICE for home buyers and building owners: water contaminants, water test procedures, well shock procedures, preventing drinking water contamination, and CHEATING ON WATER TESTS in that document.

Suggested citation for this web page

CONTAMINANT CLASSES, in WATER at - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.


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