About 25% of the county's 10,520 residents. Rank 21 of 93 in Nebraska.
95% range 111 to 178 private-well users (2010 base year). Rank 27 of 93 in Nebraska.
Highest potential (average indoor radon may be greater than 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 Colfax 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:
- Nebraska Extension (NebGuide G907, revised December 2025) suggests testing private wells every year for coliform or E. coli bacteria and nitrate as general indicators of safety. It says these tests also should be considered after flooding or when you notice any change in taste, color or smell. source
- Nebraska Extension says to test for bacteria when users have repeated bouts of intestinal illness, when an infant, a person with a weakened immune system or an elderly person starts using the water, after repairs or changes to the well or water system, when starting a well that has not been used for a long time, and after shock chlorination. Test for nitrate when a pregnant woman, a woman planning a pregnancy, a nursing woman, an infant under 6 months old or a person with a weakened immune system starts using the water. source
- To judge year-round bacterial safety, Nebraska Extension suggests testing for bacteria in late spring or early summer during wet weather. Testing in very dry weather or when the ground is frozen may be less useful. source
Arsenic. USGS estimates that about 140 people using private wells in Colfax County had arsenic above 10 µg/L, EPA's limit for public water (2010 base year; 95% range 111 to 178). 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 Colfax 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.
Show the numbers
| Item | Value | Note |
|---|---|---|
| Douglas County | 2,758 people (2010 base year) | |
| Sarpy County | 1,748 people (2010 base year) | |
| Buffalo County | 1,064 people (2010 base year) | |
| Lincoln County | 1,001 people (2010 base year) | |
| Dawson County | 693 people (2010 base year) | |
| Colfax County (this county) | 140 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 Colfax 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. 1 public system that serve ZIP codes mainly in Colfax 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 Nebraska
- For help choosing the right test for a particular water problem, the Nebraska Public Health Environmental Laboratory (NPHEL) directs private clients to the Drinking Water Program of the Nebraska Department of Water, Energy, and Environment (DWEE). source
- Nebraska Extension notes that local rules may be stricter than the state's. It suggests contacting your county and city health, environmental, zoning or planning departments about any local requirements for private water supply testing. source
Buying a home with a well in Colfax County
Loan test (FHA, VA, USDA) in Colfax County, NE
- 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 Colfax County
None of the labs on our Nebraska list has an address in Colfax 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 Nebraska 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)
- Nebraska DHHS - Certified Laboratories (drinking water) (no date printed; PDF created 2024-05-22 (file metadata))
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