Colorado Private Well Water Quality 2026

Colorado’s Military PFAS Crisis — How It Started

Colorado holds a grim distinction in the national PFAS story: the Security-Widefield area of El Paso County, south of Colorado Springs, was among the first communities in the US to publicly identify large-scale PFAS contamination from a military base in 2016. The source was aqueous film-forming foam (AFFF) used in firefighting training exercises at Peterson Air Force Base — possibly as far back as the 1970s. Over decades, PFAS leached into the Widefield aquifer and migrated into municipal wells serving Security, Widefield, and Fountain.

All 32 of the Security Water and Sanitation District’s municipal wells ultimately measured PFAS contamination at levels above the EPA’s 2016 chronic health advisory of 70 ppt. At one well, federal testing showed PFAS at 1,370 ppt — nearly 20 times higher than the then-advisory level. The EPA recommended pregnant women and small children should not drink local water. A subsequent CDC blood study of Security-Widefield residents found levels of PFHxS up to 6.8 times the national average and PFOA up to 1.2 times the national average — the direct result of years of contaminated drinking water.

Private wells in the affected area are a separate, less-monitored concern. When El Paso County and CDPHE tested 16 private wells south of Peterson Air Force Base, 13 of those 16 wells showed PFAS contamination, at levels ranging from 100 to 260 ppt. Private well owners were not eligible for the ATSDR’s 2020 community exposure assessment — ATSDR explicitly noted that private well owners in the affected area should consider having their wells tested independently.

The Peterson contamination triggered a remediation response: the Air Force funded a $9 million ion exchange treatment facility for Fountain’s municipal water, and Security Water District now sources uncontaminated surface water from Pueblo Reservoir. But private well owners in surrounding areas remain responsible for testing and treating their own supplies.

Buckley Space Force Base — A Second Front Range Threat

Buckley Space Force Base in Aurora presents a distinct PFAS risk. A 2019 Army Corps of Engineers investigation found PFAS contamination at five of six locations tested on the base — in some cases at concentrations 3,000 times above EPA screening limits. On-base PFAS measurements have reached 205,000 ppt combined PFOA and PFOS, compared to the current federal MCL of 4 ppt. More than 550 private water wells are located within four miles of the base, according to the Colorado Division of Water Resources. Three private water supply wells in Commerce City were shut down in 2018 after PFAS contamination was confirmed there.

Colorado sits fifth nationally for the number of private well contamination cases linked to military bases, according to a November 2023 Environmental Working Group report that identified 105 private drinking water wells near Colorado military installations — 101 near Peterson Space Force Base and four near Schriever Space Force Base — with PFAS above the EPA’s 4 ppt standard. Critically, the EWG noted that all 105 wells fell below the Department of Defense’s separate action threshold of 70 ppt, meaning the DoD was not obligated to provide alternative drinking water to any of these well owners. The wells are contaminated above the federal safety limit, but their owners receive no federal remedy.

Other Well Water Risks in Colorado

PFAS is not the only risk for Colorado well owners. The state’s geology and land use create several additional contamination concerns that vary significantly by region:

Nitrate: Common on the Eastern Plains and in irrigated agricultural valleys, where fertiliser and manure runoff from farming operations leaches into shallow groundwater. High nitrate levels above 10 mg/L are an immediate health risk for infants under six months. CDPHE identifies nitrate as one of the most frequently detected contaminants in Colorado’s rural well water data.

Arsenic: Elevated arsenic levels are found in parts of Western and Southwestern Colorado and in some Front Range aquifers, due to natural geology. Arsenic is colourless and tasteless — it cannot be detected without laboratory testing. Long-term exposure is linked to cancer and cardiovascular disease.

Uranium and radium: Some Front Range aquifers and Western Slope wells show elevated uranium and radium, naturally occurring from Colorado’s geology and legacy uranium mining activity. DrillerDB’s Colorado well guide notes uranium and radium contamination specifically in these regions.

Fluoride: Elevated fluoride levels are found in the Four Corners area of Southwestern Colorado, from natural geological sources. Long-term exposure above 4 mg/L (the EPA MCL) can cause skeletal fluorosis.

Bacteria and hardness: Coliform bacteria contamination is a risk statewide, particularly in older wells with inadequate seals or those near septic systems. Almost all Colorado wells also have hard water from dissolved calcium and magnesium — a cosmetic issue rather than a health risk, but one that significantly affects appliance lifespan and water taste.

Regulatory Situation for Colorado Well Owners

Private residential wells in Colorado are not regulated under the Safe Drinking Water Act at either federal or state level. CDPHE explicitly states it does not regulate the water quality of private wells — only public water systems fall under its jurisdiction. Testing and treatment of a private well is entirely the responsibility of the individual well owner. Well permits are issued by the Colorado Division of Water Resources (DWR), but permit issuance has nothing to do with ongoing water quality monitoring.

Colorado has no state-level PFAS MCLs for private wells. Federal PFAS MCLs — 4 ppt each for PFOA and PFOS — apply only to public water systems, not private wells. The original EPA compliance deadline was 2029; in May 2025, the Trump administration announced its intent to extend this to 2031 for PFOA and PFOS, while also proposing to rescind MCLs for four other PFAS compounds. These changes affect only public water systems — private well owners face no regulatory requirement to test or treat regardless of the deadline.

Colorado does stand out for one notable proactive measure: CDPHE’s PFAS Testing and Assistance Program (PFAS TAP), launched in 2024, offers free PFAS testing to all private well owners in Colorado and free water filters to income-eligible households whose wells exceed EPA MCLs. In 2024, the programme piloted in Park County. In 2025 it expanded to Gilpin, Grand, and Pueblo counties. This is one of the most accessible free well testing programmes in the US.

Check our Colorado municipal water quality page for city-by-city tap water data, or see our pages for Denver and Colorado Springs. Use our live boil water notice tracker for active advisories across the state.

Known High-Risk Areas in Colorado

If you live near any of the following locations, well water testing is urgent — not precautionary.

How to Test Your Colorado Well Water — and What to Do Next

Colorado’s PFAS TAP programme makes well testing more accessible here than in most US states. Any private well owner in Colorado can apply for free PFAS testing through CDPHE at cdphe.colorado.gov/pfas/pfas-health/pfas-testing, or contact the programme at 303-906-8052. If your well result exceeds EPA MCLs and you are income-eligible, you may also qualify for a free filter — apply before purchasing filtration independently.

For all other contaminants — nitrate, arsenic, uranium, bacteria — use a CDPHE-certified drinking water laboratory. Your local county health department can advise on certified labs in your area and flag any locally-known risks specific to your groundwater basin.

For filter options, our well water filter guide covers reverse osmosis systems for PFAS and arsenic, UV disinfection for bacteria, and whole-house well systems for comprehensive treatment. You can also browse our full water filter solutions page or check your ZIP code for local water quality context.

For other Western well water risks, see our page on Michigan wells — the state with the most confirmed PFAS sites nationally. Return to the private well water directory to find your state.