About 4% of the county's 204,737 residents. Rank 11 of 15 in Arizona.
95% range 388 to 580 private-well users (2010 base year). Rank 9 of 15 in Arizona.
Moderate potential (average indoor radon may be between 2 and 4 pCi/L). EPA says the map should not be used to decide whether an individual home needs testing.
Labs with an address in this county, from the official state lists on this site, matched by ZIP code.
What to test for in Mohave 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:
- The Arizona Department of Health Services (ADHS) well owner guide lists a testing schedule. Test all new wells for arsenic, total coliform bacteria, fluoride, lead, nitrates, total dissolved solids (TDS) and uranium. Then test once a year for total coliform bacteria and nitrates, and every 5 years for arsenic, fluoride and uranium. Also test when there are known well water problems in your area, after problems near your well (flooding, wildfire, land disturbances, nearby waste disposal sites), when the water's taste, color or odor changes, or if anyone in your family has an unexplained illness. source
- University of Arizona Cooperative Extension (2011) adds: besides yearly testing, test whenever the taste, odor or color of your water changes, and before and after installing any type of water treatment system. source
Arsenic. USGS estimates that about 477 people using private wells in Mohave County had arsenic above 10 µg/L, EPA's limit for public water (2010 base year; 95% range 388 to 580). 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 Mohave 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.
Show the numbers
| Item | Value | Note |
|---|---|---|
| Maricopa County | 3,884 people (2010 base year) | |
| Yavapai County | 3,836 people (2010 base year) | |
| Yuma County | 1,859 people (2010 base year) | |
| Apache County | 1,616 people (2010 base year) | |
| Cochise County | 1,260 people (2010 base year) | |
| Mohave County (this county) | 477 people (2010 base year) |
USGS model estimate for broad screening, not a measurement of any well. Only a test tells you about your own well. Source: USGS, Estimated county level domestic well population with arsenic greater than 10 micrograms per liter (Ayotte, Medalie and Qi, 2017), accessed 2026-11-01.
PFAS in public water near Mohave County (public supply, not your well)
This is public water data, not your well. A private well draws its own groundwater, which can have more or less PFAS than the public supply nearby. Only a test of your well tells you.
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. 13 public systems that serve ZIP codes mainly in Mohave County reported results. 3 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.
| Public water system | System ID | Highest PFOA (ng/L) | Highest PFOS (ng/L) |
|---|---|---|---|
| Hildale - Colorado City | UTAH27006 | 26 | |
| Epcor Water - Mohave | AZ0408032 | 5.3 | 7.3 |
| Epcor Water - North Mohave Valley | AZ0408068 | 5.5 |
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 Arizona
- Because groundwater quality differs across Arizona, University of Arizona Cooperative Extension says it is best to check with your drinking water agency or local health department about what to test for, as there may be local pollution issues. source
- The ADHS lab licensing office keeps a Private Well Owner Resources list. It links to wellowner.org (finding a well contractor and a drinking water testing lab), EPA's private well pages and an Arizona Department of Environmental Quality pamphlet on what private well owners should do after a fire. source
Buying a home with a well in Mohave County
Loan test (FHA, VA, USDA) in Mohave County, AZ
- VA. Test results are valid for 90 days from the date the local health authority certifies them, unless the local authority says otherwise. VA’s chapter names no list of contaminants: the water must meet the local health authority’s requirements, or EPA guidelines where it has none. Your lender may ask for specific tests.
- FHA. A well test is required in the situations FHA’s handbook lists, among others, and the report may not be more than 180 days old at disbursement.
- USDA. Guaranteed loans need a water quality test for a private well, done by the local health authority or a state-certified lab, and no more than 180 days old at closing.
Lenders can ask for more (extra tests, a particular lab, who takes the sample): ask your lender before you book. Federal rules as read on Nov 3, 2026 source 1 source 2 source 3. Full comparison: VA, FHA and USDA well water test requirements. Loan test kits sold by mail, with price and days to results: kits compared.
State-certified labs in Mohave County
Labs on the Arizona list whose own websites say they take homeowner samples: Aquatic Consulting & Testing, Inc. (Tempe), Complete Analytical Services, LLC (Tucson), Inner Basin Environmental, LLC (Flagstaff), Mohave Environmental Labs (Holbrook), Nortest Analytical (Flagstaff), Sacred Water Testing LLC (Show Low), Turner Laboratories, Inc. (Tucson). Use Check my ZIP to sort labs by distance.
See all Arizona labs in the finder and filter by the test you need and by labs that take homeowner samples.
- USGS, Estimated use of water in the United States, county-level data for 2015 (Dieter et al., ver. 2.0, 2018)
- USGS, Estimated county level domestic well population with arsenic greater than 10 micrograms per liter (Ayotte, Medalie and Qi, 2017)
- U.S. EPA, Map of Radon Zones, county list (EPA 402/A-16/001)
- U.S. Census Bureau, 2020 ZCTA to county relationship file (lab ZIP codes to counties)
- ADHS Safe Drinking Water Commercial Lab List (List of Arizona Certified Commercial Drinking Water Laboratories) (current as of Saturday, November 7, 2026)
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