What to test well water for: 4 tests every year
Test a private well every year for total coliform bacteria, nitrate, total dissolved solids and pH, the four tests CDC and EPA name. Add tests for iron, lead, arsenic, pesticides or fuel compounds when your house or land gives a reason. A coliform and nitrate test runs $20–$112 at public labs.
1,Key figures
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The annual four
CDC says to test your well at least once each year for total coliform bacteria, nitrates, total dissolved solids and pH, and that every well owner should test for nitrate yearly. EPA gives the same list and says to test more often if young children, older adults, or pregnant or nursing people live in the home. Coliform shows whether surface water or waste is reaching the well. Nitrate has a federal limit of 10 mg/L as nitrogen. TDS and pH are nuisance measures: EPA's secondary standards are 500 mg/L for TDS and 6.5 to 8.5 for pH.
Tests to add, and why
EPA ties extra tests to what you see or what is nearby.
| If you have | Test for |
|---|---|
| Stained fixtures or laundry | Iron, copper, manganese |
| Intensive farming nearby | Nitrate, nitrite, pesticides, coliform |
| Lead pipes or old plumbing | pH, lead, copper |
| Mining nearby | Metals, pH |
| Fuel odor or buried tanks | Volatile organic compounds |
| Salty taste | Chloride, TDS, sodium |
| A radon region | Radon |
Sources2
When to test right away
Do not wait for the annual test if a well repair or replacement part was just installed, if flooding or construction has disturbed the ground nearby, if neighbors report a groundwater problem, or if the water changes in taste, color or smell. CDC adds two household triggers: a pregnancy, or a child moving in. Your local health department can tell you which other contaminants are common where you live.
Common questions
Do I need to test for arsenic?
It is not on the annual list, but CDC names it as a test to ask your local health department about. The federal limit is 0.010 mg/L.
What should a new well be tested for?
Nebraska Extension says a new private well needs a baseline nitrate and bacteria test. Many labs sell a new-well package; UW-Stevens Point's NR 812 driller package is $61.
For the cost of a finished well in your state, see what drilling a well costs.
Sources
- Guidelines for Testing Well Water , CDC. Accessed November 9, 2026. July 1, 2024
- Protect Your Home's Water (Private Wells) , U.S. EPA. Accessed November 9, 2026. Last updated February 26, 2026
- Well Water Testing , Indiana Department of Health Laboratories. Accessed November 8, 2026. Undated. $10.00 for bacteria; $10.00 for nitrate.
- Environmental Services Fee Schedule (approved 2025-09-19) , Westchester County Department of Laboratories & Research (NY). Accessed November 8, 2026. Total coliform and E. coli P/A $32.10; nitrate as N $80.25; Well Water Package A (Private Well Testing Law) $583.10.
- National Primary Drinking Water Regulations , U.S. EPA. Accessed November 9, 2026. Last updated August 31, 2026
- Secondary Drinking Water Standards: Guidance for Nuisance Chemicals , U.S. EPA. Accessed November 9, 2026. Last updated May 26, 2026
- Nitrate in Drinking Water , University of Nebraska-Lincoln (Nebraska Extension), Becky Schuerman. Accessed November 9, 2026. September 9, 2020
- 2026 Analysis Price List (Water and Environmental Analysis Lab) , University of Wisconsin-Stevens Point, Center for Watershed Science and Education. Accessed November 8, 2026. Prices effective through 2026-12-31. Coliform P/A $30; nitrate+nitrite $29; homeowner package $78; new well / well drillers NR812 compliance package $61.
How these figures are built: methodology. Updated November 2026.