Photograph of a total <EM>Coliform</EM> test with <EM>Coliform</EM> present - liquid turns yellow Guide to Water Contaminants & Water Tests
Index to Articles on Water Contamination Limits, Water Testing Advice & Procedures

  • WATER TESTS for CONTAMINANTS - CONTENTS: Water testing advice: how, when, and why to test water, what to test for in drinking water supply. Water potability testing guide - water bacteria test guide. Articles Describing Types of Water Potability Tests, Water Purity Tests, Test for Other Water Contaminants. How to conduct water tests, what water tests to order, how to avoid dishonest or cheating on water tests
  • POST a QUESTION or READ FAQs about when, how, and why to test well water for contamination: advice for property or home buyers and property or home owners who use a private well for drinking water
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This article gives advice on water testing for property or home buyers or home owners, with focus on a strategy for assuring the quality of well water by site inspection, property history investigation, and strategically-selected water tests for contamination.

The articles listed on this water testing advice page will answer most questions about drinking water testing, focused on testing water supplied from wells, & water tanks as well as many other building plumbing system inspection or defect topics.

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Water Testing Advice

How to Investigate for Water Contaminants at a New or Unknown Property or Well

General advice on water testing when buying a rural property:

The minimum test for water potability elected by many property owners or buyers looks only at bacteria. Some government lenders require more extensive tests such as the FHA and Title-5 water potability testing series. Those and similar "water test package" deals offered by water testing labs can be a good way to spend your water testing dollars as they test for the most common contaminants found in well water in many areas.

Watch out for "False Negative" assurances that Well Water is "Pure"

First of all, no water test assures against all possible contaminants in water. Second, water tests that focus on water potability (is the water safe to drink) may miss other important water conditions, such as water that is too high in mineral content, clogging pipes and water heaters (see MEASURE WATER HARDNESS), or water that is too acidic or corrosive, causing leaks in copper piping (see CORROSIVITY or ACIDITY of WATER).

Watch out: even so, property buyers should beware of ordering water tests arbitrarily, Because of the enormous number of potential chemical contaminants that might show up in water, there is a risk of accepting a "false negative" result, that is, a risk of assuming that there are no contaminants in drinking water after a specific water contaminant tests shows a negative result . It may simply be the case that a contaminant that is present was not detected because it was not within the scope of the tests performed.

Therefore to be more confident about the quality of water at a property whose water and land history may be unknown, we recommend a series of escalating steps in water testing and other investigative measures. At several points in the investigation process a property buyer or new owner may decide that the information obtained so far provides enough confidence, or that the information suggests that additional levels of water testing are appropriate.

Site investigation for well water quality concerns

This important step in investigating well water quality includes

A visual inspection for things that might raise a red flag: evidence of chemical, fuel, or fertilizer storage on the property or nearby at sites that drain onto the property, nearby industry (industrial chemicals), nearby orchards (pesticides) or farms (fertilizers) whose land drained across or onto the property.

Among the most basic observations will be the location of the well and its proximity to septic system drainfields, barns, livestock pens, or farm chemical storage tanks or fuel tanks. And of course the type of well (dug, driven point, steel well casing) and depth also have implications for the probability of contamination by surface runoff or subsurface contaminants.

Investigation by asking neighbors, the local health department, and nearby water testing laboratories to determine if they know of specific water quality problems that have been discovered in the neighborhood. This step can sometimes provide surprising payoff such as questions by one of our clients whose Pawling NY well had tested as "OK" for several contaminants.

A neighbor pointed out that a paper company had for years dumped acetone and other waste chemicals in an empty field across the street from the client's well. Testing found unusual levels of acetone in the water - an uncommon contaminant as acetone is so volatile, and not something that anyone would have tested for without a clue from a helpful neighbor.

Professional investigation services are available from environmental inspection and testing firms who will research government data bases of known sources of water contamination, but watch out: such investigations may not disclose small local industries or contamination sources.

Choosing Specific Water Test Lab Tests for Water Quality

Informed by step 1 above, the minimum water test that is performed is a bacteria test or "water potability test". While the minimal "presence/absence" test is popular and inexpensive, the test gives a "go / no-go" result (there is or is not a coliform bacteria level at or above 1 colony forming unit (CFU) per 100 ml of water). Keep in mind that no water test assures a zero level of bacteria in water nor do health regulations require it. A more costly water test for bacteria provides an actual count of the bacteria level found, if above certain thresholds - this is a much more useful test as it is diagnostic both before and after attempts to correct a bacteria problem.

Bacteria testing does not itself assure anything about the presence or absence of chemical contaminants or aesthetic contaminants (silt, odors, hardness) in well water. But nevertheless, if a water test "fails" a bacteria test, because a common source of high bacterial levels in well water is the leakage of surface runoff into a well, that means that there is also a higher risk of the presence of other contaminants that might be found on the ground surface (pesticides, fertilizers).

Therefore even if a home owner/buyer decides to perform only the most minimal bacterial testing, the result can be a red flag that more thorough testing for other contaminants is in order.

Where a well is on or near farmland or orchards, water testing labs will often recommend one of two pesticide tests (depending on property age and whether or not it's appropriate to test for DDT or chlordane or newer pesticides, as well as tests that can detect common ingredients in fertilizers.

At a property in Dutchess County, NY, where we found a "permanently-parked" trailer that had been used by Terminix™ to store pesticides I was worried about possible storage leaks and thus pesticide contamination in the nearby well. Tests for pesticides found that there was no contamination of the well nor of soil around the trailer. The pest control company had been careful.

But a subsequent investigation of the property's history disclosed that a metal plating shop had been present in one of the buildings on the site. Tests found high levels of chromium contamination of soils, water, and even a nearby stream bed, resulting in a serious environmental contamination issue that involved the new property owner as well as local, state, and federal environmental officials.

Where the visual inspection or a study of the property history discovers specific potential sources of contamination, it makes sense to discuss these with the water test lab director to decide what tests are most useful to perform.

Watch out: this discussion has focused on well water quality - what is "in" the well water that may make it unsafe or unpalatable to drink. We also mention and refer readers to other important water conditions, such as water that is too high in mineral content, clogging pipes and water heaters

(see MEASURE WATER HARDNESS), or water that is too acidic or corrosive, causing leaks in copper piping

(see CORROSIVITY or ACIDITY of WATER). An equally important question is "does the well provide enough water" - a topic discussed



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