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Uranium is widespread in Douglas County wells.

1 widespread, 2 worth checking, 4 rare out of 7 health checks.

From 35 wells tested in Douglas County since 2000; your own well needs its own test. How to read this

Tested wells over the limit DouglasColorado
Uranium16%5 of 31Manganese10%3 of 31Arsenic6%2 of 31Nitrate3%1 of 35Radon0%0 of 11Lead0%0 of 31Fluoride0%0 of 31
GermsTest every year, whatever the chart says
Coliform bacteria0%0 of 6E. coli0%0 of 6
StainsNot a health risk
Iron stains19%6 of 31

Rare: under 5%Worth checking: 5 to 15%Widespread: 15%+

Lab results: Water Quality Portal (USGS and EPA)

Who drinks from a well here

About 1 in 14 people 26,161 people

Nobody else tests these wells. Only you do.

People on wells: EPA researchers' 2020 estimate

How deep wells go here

385 ft Near the surface: fertilizer, germs Deeper: arsenic, uranium from rock 800 ft

Deep wells: fewer surface germs, more minerals from the rock.

Well depths: US Groundwater Well Database

Radon risk (a gas from rock)

Likely here. Test your home's air first.

Radon zones: EPA map

Here's how Douglas County compares with Colorado and the counties around it.

Each result puts Douglas County next to the 5 counties that border it, on the chart's 0 to 50% scale.

This one is widespread in Douglas County wells.

Uranium5 of 31 wells over

About 2 in 10 wells tested here from 2003 to 2011 were over the EPA limit of 30 µg/L, against about 2 in 10 across Colorado. Half the results were under 1.8 µg/L, and the top 1 in 10 were 56 µg/L or more. That's a smaller share than in 7 of the 12 other Colorado counties with 10 or more tested wells.

Douglas and its neighbors
Arapahoe28%
Elbert24%
Douglas16%
El Paso0%

Too few tested to show: Jefferson, Teller.

Uranium guide

These 2 are worth checking in Douglas County.

Manganese3 of 31 wells over

3 of 31 wells tested here from 2003 to 2011 were over the EPA health advisory of 0.3 mg/L, against about 2 in 10 across Colorado. Half the results were under 0.017 mg/L, and the top 1 in 10 were 0.25 mg/L or more. That's a bigger share than in 10 of the 19 other Colorado counties with 10 or more tested wells, leaving out 1 county whose results are likely overstated.

Douglas and its neighbors
Arapahoe27%
Elbert27%
Douglas10%
El Paso8%

Too few tested to show: Jefferson, Teller.

Manganese guide

Arsenic2 of 31 wells over

2 of 31 wells tested here from 2003 to 2011 were over the EPA limit of 10 µg/L, against about 1 in 8 across Colorado. Half the results were under 1.8 µg/L, and the top 1 in 10 were 5.3 µg/L or more. That's a bigger share than in 7 of the 11 other Colorado counties with 10 or more tested wells, leaving out 2 counties whose results are likely overstated.

Douglas and its neighbors
Elbert7%
Douglas6%
Arapahoe5%
El Paso0%

Too few tested to show: Jefferson, Teller.

Arsenic guide

These 4 are rare in Douglas County.

Nitrate1 of 35 wells over

1 of 35 wells tested here from 2000 to 2011 was over the EPA limit of 10 mg/L, against about 1 in 10 across Colorado. Half the results were under 1.4 mg/L, and the top 1 in 10 were 10 mg/L or more. That's a bigger share than in 9 of the 17 other Colorado counties with 10 or more tested wells, leaving out 4 counties whose results are likely overstated.

Douglas and its neighbors
Arapahoe19%
El Paso10%
Elbert3%
Douglas3%

Too few tested to show: Jefferson, Teller.

Nitrate guide

Radon in water0 of 11 wells over

None of the 11 wells tested here from 2004 to 2005 were over 4,000 pCi/L, a level the EPA proposed, against about 1 in 8 across Colorado. Half the results were under 1,020 pCi/L, and the top 1 in 10 were 2,020 pCi/L or more. Douglas County had none, while 2 of the 3 other Colorado counties with 10 or more tested wells had at least one.

Douglas and its neighbors
El Paso6%
Douglas0%
Elbert0%

Too few tested to show: Arapahoe, Jefferson, Teller.

Radon guide

Lead0 of 31 wells over

None of the 31 wells tested here from 2003 to 2011 were over the EPA action level of 15 µg/L, against about 1 in 26 across Colorado. At least half the results were too low for the lab to measure, and the top 1 in 10 were 0.32 µg/L or more. Douglas County had none, while 3 of the 12 other Colorado counties with 10 or more tested wells had at least one.

Douglas and its neighbors
Arapahoe0%
Douglas0%
El Paso0%
Elbert0%

Too few tested to show: Jefferson, Teller.

Lead guide

Fluoride0 of 31 wells over

None of the 31 wells tested here from 2003 to 2011 were over the EPA limit of 4 mg/L, against about 1 in 26 across Colorado. Half the results were under 0.71 mg/L, and the top 1 in 10 were 1.8 mg/L or more. Douglas County had none, while 4 of the 16 other Colorado counties with 10 or more tested wells had at least one, leaving out 3 counties whose results are likely overstated.

Douglas and its neighbors
Arapahoe0%
Douglas0%
El Paso0%
Elbert0%

Too few tested to show: Jefferson, Teller.

None of the 6 Douglas County wells tested for bacteria had it, but every well needs a yearly test.

Coliform bacteria0 of 6 wells had it

None of the 6 wells tested here in 2003 had coliform bacteria, against about 2 in 10 across Colorado.

Bacteria guide

E. coli0 of 6 wells had it

None of the 6 wells tested here in 2003 had E. coli, against about 1 in 42 across Colorado.

E. coli means human or animal waste is getting in, so if a test of your Douglas County well finds it, boil drinking water until the well is fixed.

Bacteria guide

Iron reached staining levels in 6 of 31 tested wells, and it isn't a health risk.

Iron stains6 of 31 wells had it

About 2 in 10 wells tested here from 2003 to 2011 had enough iron to stain (0.3 mg/L), against about 2 in 10 across Colorado.

Douglas and its neighbors
Elbert20%
Douglas19%
Arapahoe15%
El Paso13%

Too few tested to show: Jefferson, Teller.

Iron guide

Most of the 35 wells tested in Douglas County were last tested before 2010.

35 wells had a test in the 2000s and 2 in the 2010s.

An old result shows the water as it was then, so treat these 35 wells as a starting point and test your own.

Most Douglas County wells in these records were tested for research or because someone suspected a problem, which can push the shares above what a typical home well would show (how we read the numbers).

One mail-in lab test covers the 5 things to check in Douglas County.

  • Bacteria
  • Nitrate
  • Uranium
  • Manganese
  • Arsenic

What Colorado offers well owners

Half the household wells here are shallower than 385 feet.

That comes from 11,424 household wells in Colorado's drilling records. Most wells of every kind here are 275 to 563 feet deep. Wells as deep as Douglas County's are usually better protected from fertilizer and bacteria at the surface, but they can pick up more of what's in the rock, like arsenic and uranium. Typical household wells here go deeper than in 62 of the 63 other Colorado counties with enough drilling records.

Look up your own well's depth in Colorado's well record search, or see how to find it.

Well depths: US Groundwater Well Database

Here's what we know about radon and PFAS in Douglas County.

Douglas County is in the EPA's highest radon zone. Radon from well water adds to the radon in your indoor air, so test your air first, and your water too if the air is high. Radon guide

Between 2023 and 2025 the EPA had 13 town water systems in Douglas County test for PFAS. 2 of them had at least one test above 4 ng/L, the new EPA limit for PFOA and PFOS. The highest single result was 5.6 ng/L of PFOA. No well in Douglas County has public PFAS results, so the town systems are the best clue to what's in the groundwater nearby. PFAS guide

Radon zones: EPA Map of Radon Zones. PFAS: EPA tests of town water systems, 2023 to 2025

Next door to Douglas County
El PasoElbert
Elsewhere in Colorado
WeldLa Plata

All of Colorado

Get a yearly reminder to test your Douglas County well

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Questions people ask about well water in Douglas County

Is well water in Douglas County safe to drink?

5 of 31 wells tested in Douglas County had uranium over the limit, about 2 in 10. Across Colorado it's about 2 in 10. That's a smaller share than in 7 of the 12 other Colorado counties with 10 or more tested wells. So test your own well for uranium before you count on it.

Can I get my well tested for free in Douglas County?

CDPHE offers free PFAS testing for private wells through its PFAS Testing and Assistance Program. If not, use a lab Colorado has certified for drinking water. Ask for bacteria, nitrate, uranium, manganese and arsenic, the tests that matter most in Douglas County.

How deep are wells in Douglas County?

Half the household wells here are shallower than 385 feet. Typical household wells here go deeper than in 62 of the 63 other Colorado counties with enough drilling records.

How does Douglas County compare with the counties around it?

For uranium, the share of tested wells over the limit: 2 of the 3 neighboring counties with data had a higher share than Douglas County, at 16%. Arapahoe had the most, at 28%. Groundwater doesn't stop at county lines, so Arapahoe's 28% is worth knowing about if you live near it.

How often should I test my well in Douglas County?

None of the 6 wells tested for bacteria in Douglas County had it, but the CDC still says to test for bacteria and nitrate every year, and right away after a flood, a repair, or any change in taste or smell.

By the Tested Water teamData from the USGS, EPA and Department of Public Health and EnvironmentUpdated November 8, 2026

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Where the Douglas County numbers come from

  • People on wells: 26,161 in Douglas County, from EPA estimates built on the 2020 Census (Murray et al.).
  • Lab tests: 319 well water samples from 35 wells in the Water Quality Portal, run by the USGS and EPA, 2000 to 2011.
  • Well depths: 11,424 Colorado drilling records for Douglas County, gathered in the US Groundwater Well Database (Lin and others, 2024).
  • Neighboring counties: the 5 counties that share a border with Douglas County, from the Census Bureau's county adjacency file.
  • PFAS: EPA tests of 13 town water systems in Douglas County under the Fifth Unregulated Contaminant Monitoring Rule, 2023 to 2025.
  • Radon: Douglas County is zone 1 on the EPA Map of Radon Zones.
  • State programs and links: Department of Public Health and Environment, checked November 1, 2026.
Download this county's data (CSV)How we read these numbersReport an error
One lab test covers what to check in Douglas CountyFind a lab test