Well water testing in Sierra County, New Mexico

What to test for in Sierra 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:

• NMED's Drinking Water Bureau suggests testing every spring for common contaminants such as coliform bacteria and nitrates. Its list of recommended tests is bacteria, nitrate and arsenic every year, and uranium every five years. NMED says this is general guidance, not a regulatory requirement. source
• NMED also suggests considering a test after a new well is installed, if there is no record of earlier testing, and when there is unexplained illness in the household, someone is pregnant or nursing a child under 6 months, the water's taste, color or odor changes suddenly, after a septic system failure, wildfire, flood or prolonged drought, or when neighbors have water quality problems. source
• Depending on your location or concerns, NMED lists other tests you might consider: fluoride, lead, iron and manganese, total dissolved solids, volatile organic compounds (in industrial areas or near fuel storage tanks), and pesticides and herbicides (near agricultural areas or heavy pesticide use). source

Arsenic. USGS estimates that about 111 people using private wells in Sierra County had arsenic above 10 µg/L, EPA's limit for public water (2010 base year; 95% range 86 to 142). 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 Sierra 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 Sierra 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 Sierra County reported results. 1 of them had at least one sample with PFOA or PFOS at or above 4.0 ng/L, and 1 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 New Mexico

• In an August 13, 2026 release, NMED said private well users can bring water samples to NMED field offices statewide, where staff screen them for nitrate, iron and fluoride at no cost. NMED calls this an initial screening that does not replace more comprehensive testing by a certified lab, and says similar tests from commercial labs cost $100 to $125. source
• NMED's Ground Water Quality Bureau runs free Water Fair events, about 10 per state fiscal year (July 1 to June 30) in rural communities. Staff use portable equipment to test well water for arsenic, nitrate, electrical conductivity, pH, fluoride, sulfate and iron. source
• For the field office screening, NMED asks for at least one quart of cold kitchen tap water in a clean, covered glass or plastic container, delivered soon after collection with a completed Well Testing Form. Results are mailed on the form, with acceptable levels on the back. Conductivity and organic vapor may also be tested if instruments are available. source
• NMED's August 2026 release also lists targeted programs: private well testing for heavy metals and PFAS near the Hermits Peak-Calf Canyon burn scar, and PFAS testing with free home filtration systems for affected private well owners in Santa Fe and Curry counties. source

Buying a home with a well in Sierra County

State-certified labs in Sierra County

None of the labs on our New Mexico list has an address in Sierra 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 New Mexico labs in the finder and filter by the test you need and by labs that take homeowner samples.