Well water testing in Jefferson County, Oregon

What to test for in Jefferson 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:

• OHA says Oregon requires well testing only when a property with a well is sold, but it recommends testing for coliform and E. coli bacteria every year, nitrate every year, and arsenic every 3 to 5 years. You may need to test more often if the well has a history of contamination, the septic system recently malfunctioned, household members have a stomach illness, infants drink the water, or any equipment has broken. OHA lists typical costs of $20 to $40 for the bacteria and nitrate tests and $25 to $45 for arsenic. source
• If arsenic is above 8 ppb, OHA says to retest; if levels stay high, install a treatment system and keep testing every year at the faucet you drink from and every 3 years at the wellhead. source
• Oregon State University's Well Water Program advises testing for coliform bacteria at least once a year, when taste or color changes, after work on the well, if the well cap is not secure, or if surface water stands around the well. It suggests testing for nitrate if a pregnant woman or newborn will drink the water, and once a year if you live near fertilized fields, septic systems or livestock, or have had nitrate before. source

Arsenic. USGS estimates that about 77 people using private wells in Jefferson County had arsenic above 10 µg/L, EPA's limit for public water (2010 base year; 95% range 57 to 103). 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 Jefferson County in Zone 2: moderate potential (average indoor radon may be between 2 and 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 Jefferson 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. 2 public systems that serve ZIP codes mainly in Jefferson County reported results. 0 of them had at least one sample with PFOA or PFOS at or above 4.0 ng/L, and 0 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 Oregon

• The Oregon Health Authority (OHA) offers a free well water test to households in Morrow and Umatilla counties whose well is inside the Lower Umatilla Basin Groundwater Management Area (LUBGWMA) and is used for drinking and cooking (not commercial wells or public water systems). You apply for a testing voucher online. source
• In the LUBGWMA program the first test covers nitrate, arsenic, lead, total coliform and E. coli. Depending on the nitrate result, OHA and the county health departments offer free retesting; households at 10 mg/L or more qualify for free drinking water delivery, and those between 10 and 24.99 mg/L are also offered a free reverse osmosis system. OHA says free testing is not available to households outside the LUBGWMA. source
• OSU Extension's Well Water Program offers free nitrate screening of well water at many of its Groundwater Protection Education events. It also suggests contacting several certified labs about price and logistics before ordering tests. source

Buying a home with a well in Jefferson County

State-certified labs in Jefferson County

None of the labs on our Oregon list has an address in Jefferson County. Labs elsewhere in the state may take samples by mail or courier: ask the lab, and check the hold time for bacteria before you send one.

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