Water Testing: Who Actually Tests Your Water, and When It's You

Who tests your water depends on where it comes from

Three sources say the same thing in three different ways. Oklahoma State University Extension puts it most directly: "Unlike public water systems, which are regulated by federal and state agencies, the quality and safety of private well water is the sole responsibility of the well owner" Source 1: Oklahoma State University Extension, Well Water Basics, BAE-15441.

The National Ground Water Association says why. Privately owned wells serving a home "are not regulated on an ongoing basis for water quality" Source 2: National Ground Water Association, Well Owner's Guide, 2021 edition2. And the Texas Well Owner Network names the rule that draws the line: the Safe Drinking Water Act "does not regulate private wells that serve fewer than 25 people" Source 3: Texas Well Owner Network, Texas A&M AgriLife Extension, Well Owner's Guide to Water Supply3.

So the same phrase describes two different situations:

• Public water system. The supplier samples and reports on a schedule set by law. The standards it tests against are the ones covered in the guide to what makes water potable.
• Private well. Nothing is sampled unless the owner sends a sample. A well can run for years without a single test, and the water will not announce that on its own.

The one test a public-water household still owns

A utility tests the water it sends out. It does not test the water at your kitchen tap, and for two contaminants that difference matters.

EPA's drinking water regulations list the source of lead and copper as "Corrosion of household plumbing systems; erosion of natural deposits" Source 4: U.S. EPA, Ground Water and Drinking Water, National Primary Drinking Water Regulations4. The plumbing is on the house side of the meter. EPA regulates both metals through a treatment technique: water systems must control how corrosive their water is, and if "more than 10% of tap water samples exceed the action level, water systems must take additional steps" Source 4: U.S. EPA, Ground Water and Drinking Water, National Primary Drinking Water Regulations4.

That rule is written around a sample of taps across a whole system. It is not a result for your house. If your home has older plumbing, a tap-side test for lead and copper is the one piece of water testing the utility cannot do for you.

What a private well gets tested for, and how often

For a well, the schedule has a floor and three triggers. The floor comes from NGWA: test "at least annually for bacteria, nitrates, and any contaminants of local concern" Source 2: National Ground Water Association, Well Owner's Guide, 2021 edition2. Bacteria and nitrate are the two no authority leaves off the list. Everything beyond them depends on the geology and the land use around the well, which is why NGWA adds that "organizations may differ on their recommendations." The guide to what to test well water for works through that disagreement in detail.

NGWA names three reasons to test before the year is up Source 2: National Ground Water Association, Well Owner's Guide, 2021 edition2:

• A sudden change in the water. New taste, smell, color, or cloudiness.
• A chemical spill nearby. Fuel, solvents, or farm chemicals released close to the well.
• Contamination moving through the groundwater. A known plume spreading over time toward nearby wells.

One caution belongs here. If a bacteria test comes back positive, the water is not for drinking until a retest clears it. What to do about the well itself is a decision for a licensed well professional, not a weekend task.

Where to have it run

EPA's own guidance to private well owners is specific about the lab. If you think the well "may be near a source of contamination or may have been contaminated," then "have your water tested by a certified laboratory" Source 5: U.S. EPA, Secondary Drinking Water Standards: Guidance for Nuisance Chemicals5. It also names where the list lives: "A list of certified labs is available from your state's laboratory certification officer" Source 5: U.S. EPA, Secondary Drinking Water Standards: Guidance for Nuisance Chemicals5. That is a state program, not a brand.

Home test strips have a place, but it is screening, not proof. The guide to well water test kits explains which formats end in a result a health department will accept. And once a report comes back, reading well water test results covers what the numbers mean.

Requirements vary by county. Your county health department has the final word on what testing is required for a new well, a property sale, or a well in your area.

Where this fits

This post answers the first question: who is testing, and whether it is you. The next ones are already covered. Start with what to test your well water for, pick a format with the test kit guide, and read the report with the results guide. If the question is what "safe" means in the first place, potable water explains the two kinds of EPA standard.