What to do when a well fails a drinking water test - step by step action guide
How to make sure that a water test has been properly conducted - first step after a bad water test result
Guide to drinking water testing, contamination, and treatment
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The first thing to check if a well fails a drinking water potability or other test is to be sure that the test was properly conducted. Here we describe common mistakes people make when testing water and what to do about them. This series of articles explains many common water contamination tests for bacteria and other contaminants in water samples. We describe what to do about contaminated water, listing common corrective measures when water test results are
unsatisfactory. We include water testing and water correction measures warnings for home owners and especially for home buyers when certain conditions are encountered, with advice about what to do when these circumstances are encountered.
Various treatment methods for contaminated water are reviewed and the pros and cons of each are discussed.
Water Test Procedure Errors: Assure Proper Water Sample Testing Procedures Were Followed, Detecting Water Test Cheating
If a result is not satisfactory the following questions must be addressed:
Was the sample properly taken?
Water Sample Collection Procedure: (We remove the faucet, aerator which can harbor bacteria, run at least 20
minutes of water, 24 hours if house is unoccupied, and fill the container
without touching its interior.)
Water sample bottle: was a sterile water sample bottle used, a bottle provided by the water test lab?
Water sample location errors: was the water sample collected from an indoor plumbing fixture faucet, one that would normally be used to draw water for human consumption such as at a kitchen sink? If a water test person collected water from an outside hose faucet that fixture may itself have been unsanitary; if a water test person collected a water sample from plumbing components that have not been in recent use there may have been bacteria or contaminants in the piping or fixture.
Water sample delivery errors: was the water sample delivered to the water test lab at the proper time? Was the water sample refrigerated during transit? Depending on the type of water test (for bacteria for example) and the lab process used (the process must be one approved by the state health department), the water sample needs to arrive at the test lab within a specified time, such as four hours up to perhaps 12 hours. In some conditions such as hot weather it may be also necessary to refrigerate the sample, particularly if it is not being delivered to the water test lab immediately.
Did someone tamper with the water supply? See Cheating on water tests: Testing Water for Real Estate Transactions - make sure your water test is valid
Has recent repair work been done on the building plumbing or water system that was not followed by an adequate disinfection when the work was completed? (New piping, water tank, controls in the building)
Was work recently done on the well itself? Installing a new submersible (in-well) pump and well line or foot valve means pulling the piping out of the well, lying it on the (unsanitary) ground surface, and then replacing in the well. The well should have been disinfected after such work. On occasion I've found a similar problem occurring with indoor plumbing work.
Is it a new well that has not been in daily use
Was the well improperly disinfected? with inadequate concentration, contact time, or time between treatment and follow-up testing? Additional details are at
Has the building been vacant and the water system not in use for an extended period of time
Is the well properly sealed against surface and subsurface water contamination?
If the well casing top is at or below the surface of the ground it's easy for unsanitary surface runoff to enter the well and contaminate drinking water
Even if the well casing is well above ground surface level, as is usually the case with modern drilled steel-casing wells, there may be leaks into the well casing that let unsanitary surface water enter the well. Examples of leaks into the well include
Leaks at the pitless adapter where the vertical-rising well pipe inside the well exits out of the side of the steel well casing. The pitless adapter is a special plumbing fitting that handles the passage of round well piping through the vertical sidewall of the steel well casing. On some wells we have found that the installer did not have a pitless adapter at hand so s/he simply applied putty or caulk around the opening in the well casing where the well pipe exited.
Leaks in the well casing itself from cracks or splits
Water filters as a source of contamination: Are there cartridge type or R.O. (reverse osmosis) filters in use on the water system? (These can be a source of bacterial contamination.)
When is Well Disinfection Required?
If the source of the contamination is not due to an ongoing situation, for example bad ground water source, then a disinfection of the water system will solve the problem.
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General water testing and corrective measure advice: contact your local health department.
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