Test your well water

2-3.1 Who is responsible for your well water?

You are. EPA says private domestic well quality is "not regulated by the Federal Government under the Safe Drinking Water Act" and that owners answer for safe water. Mesa County Public Health said the same in May 2026 in plainer words: testing is the only way to know if water is safe.

2-3.2 What should you test for, and how often?

Test yearly as a minimum, and test sooner when something changes. EPA names four yearly tests and asks for more often with small children, elderly adults, or anyone pregnant or nursing in the home. CDC adds a spring check of the well for mechanical problems. Mesa County's Regional Lab goes further and recommends testing private wells seasonally for bacteria.

2-3.3 Where do you send a sample?

Use a certified lab, as both EPA and CDC say. On the Slope, Mesa County's Regional Lab offers a coliform present/absent test with E. coli for wells and cisterns, is certified by the state health department, and gives private well owners guidance and shock chlorination support.

We couldn't open the state health department's labs list, or the Delta County and Montrose County health pages, when this was last checked in November 2026. If you live in those counties, call the county health office and ask which certified lab it points owners to, and how to collect the sample so it counts.

1. Ask the lab for its bottle and its instructions before you collect anything.
2. Follow its timing for getting the sample back.
3. File the report with the date on your house card (§1-1).
4. Put the next test on the calendar now.

2-3.4 What do the bacteria results mean?

A positive result tells you germs may have a way in, and the two names don't mean the same thing. EPA says total coliform isn't itself a health threat but shows whether other harmful bacteria may be present, and that E. coli indicates human or animal waste. CDC says a high coliform count suggests harmful germs may be present and a positive E. coli suggests feces has entered the water. Either way, CDC points you to bottled or other safe water and the health department.

2-3.5 How does a well get disinfected?

By a contractor, as the default. CDC says, of wells after an emergency, that they "should be disinfected by a well or pump contractor, due to safety concerns." After a flood at the wellhead, EPA says to stay away from the pump while it's flooded because of shock risk, not to drink or wash with the water, and to have a well or pump contractor clean and disinfect before restart.

Outside a flood, Mesa County publishes a shock chlorination procedure as local information. The copy reviewed here was created in 2019, and the lab's page links a newer 2026 version, so ask the lab for the current one. Its cautions are worth knowing even if you hire the job: never mix chlorine with acids or ammonia, don't flush chlorinated water into a septic system, avoid draining it onto lawns, and don't chlorinate carbon filters. Where sources differ on hold time, go with CDC's at least 12 hours.

After chlorinating, follow CDC's retest schedule. Test 7 to 10 days after all chlorine is flushed, again at 2 to 4 weeks and at 3 to 4 months, then at least twice a year. Until a test confirms the water is safe, use another source or boil it: CDC gives a rolling boil for 1 minute, and EPA says three minutes above 5,000 feet, which takes in most Slope towns.