Well water testing in Knox County, Tennessee

What to test for in Knox County

Private wells are not regulated like public water: EPA advises owners to test their well every year for total coliform bacteria, nitrates, total dissolved solids and pH. Your state's own schedule:

• TDEC's Division of Water Resources strongly recommends testing private water supplies for bacteria every year. If the well tests positive, disinfect it and retest. source
• The Tennessee Department of Health suggests bacteria every year (multiple samples), chemicals such as nitrate and metals every two years, VOCs every few years if you are near industry, and radon if your home has elevated indoor radon. source

Arsenic. USGS estimates that about 16 people using private wells in Knox County had arsenic above 10 µg/L, EPA's limit for public water (2010 base year; 95% range 12 to 23). USGS describes this kind of estimate as useful "for broad screening of the population at risk", so it says nothing certain about any one well. Arsenic has no taste or smell: test for it by name.

Radon. EPA puts Knox County in Zone 1: highest potential (average indoor radon may be greater than 4 pCi/L). That map is about radon in indoor air, and EPA says it should not be used to decide whether an individual home needs testing. If radon is found in your air and you have a well, EPA suggests testing the water too: see radon in well water.

For anything specific to your home (farms nearby, old plumbing, a new baby, a smell or stain), use the which-tests checklist. When the results arrive, check your numbers against EPA's limits.

PFAS in public water near Knox County (public supply, not your well)

Under EPA’s fifth Unregulated Contaminant Monitoring Rule (UCMR 5), public water systems sampled their water for 29 PFAS between Jan 3, 2023 and Jun 17, 2026. 10 public systems that serve ZIP codes mainly in Knox County reported results. 1 of them had at least one sample with PFOA or PFOS at or above 4.0 ng/L, and 5 had at least one of the 29 PFAS measured at or above its reporting level.

4.0 ng/L (parts per trillion) is both EPA’s UCMR 5 reporting level for PFOA and PFOS and the number in EPA’s 2024 limit for public water. That limit is judged on a running annual average, so one sample at that level is not a violation. EPA proposed changes to its PFAS rules in May 2026: see PFAS in well water for the current status and who should test a well. To test your own well, find a lab certified for PFAS.

Method: a system counts for this county when it reports serving a ZIP code whose largest land part is in this county, so a system serving several counties counts in each. Source: U.S. EPA, UCMR 5 occurrence data (by state), file dated Oct 15, 2026; downloaded Nov 1, 2026.

Testing programs and help in Tennessee

• For questions about total coliform sampling, TDEC directs you to the Environmental Field Office or contract county for your location. TDEC has no funding or financing program for private wells, but links to outside financing programs. source
• The Department of Health advises reviewing your results with TDEC's Division of Water Resources; a treatment system may be needed depending on the results. source

Buying a home with a well in Knox County

State-certified labs in Knox County

Labs on the Tennessee list whose own websites say they take homeowner samples: Tennessee Tech University Water Center (Cookeville). Use Check my ZIP to sort labs by distance.

See all Tennessee labs in the finder and filter by the test you need and by labs that take homeowner samples.