Well water testing in Sheridan County, Wyoming

What to test for in Sheridan 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:

• Wyoming DEQ recommends testing for bacteria (E. coli, total coliform) and nitrates every year, and for arsenic, lead, copper, iron, manganese, sulfate and total dissolved solids every five years. It notes that uranium, radium, selenium and methane are also common in Wyoming groundwater, and that owners in areas of possible oil and gas development should test for more. source
• DEQ also says to test right away if the taste, color or odor of your water changes or someone in the household has an unexplained illness, and to test when someone in the home is pregnant, an infant, elderly or has a health condition. source

Arsenic. USGS estimates that about 131 people using private wells in Sheridan County had arsenic above 10 µg/L, EPA's limit for public water (2010 base year; 95% range 107 to 161). 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 Sheridan 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 Sheridan 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. 1 public system that serve ZIP codes mainly in Sheridan 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 Wyoming

• DEQ's Know Your Well program helps private well owners with water quality questions, including reading lab results. DEQ also points owners to the Be Well Informed web tool, which Wyoming partners on, to check results against drinking water standards. source
• DEQ says local health departments in Wyoming can give information and guidance on well water testing and health effects. source

Buying a home with a well in Sheridan County

State-certified labs in Sheridan County

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