Understanding Your Well Water in Colorado

Over 200,000 Colorado wells are permitted, and the water they produce is unregulated. The Denver Basin aquifer is declining. Radon levels are among the highest in the nation. Arsenic is rising in the San Luis Valley. If you're on a private well, nobody is testing your water but you.

The Numbers

200,000+ well permits issued in Colorado

73% of Colorado homes have high radon levels

9.9 ft/yr Laramie-Fox Hills aquifer decline rate

0 federal regulations on private well testing

Why It Matters

Colorado's geology gives us the Rockies and some of the most complex groundwater in the country. The Denver Basin aquifer system is being pumped dry on a 100-year timeline — and we're at the halfway point. Pikes Peak granite produces radon that dissolves into well water. The San Luis Valley's closed basin concentrates arsenic as drought deepens. Mancos Shale on the Western Slope leaches selenium. And 35,000+ oil and gas wells in Weld County create methane migration pathways.

Unlike public water systems, private wells are not regulated by the EPA or the state of Colorado. No one tests your water, treats your water, or notifies you if something is wrong. That responsibility is entirely yours.

Radon

Colorado is Zone 1 for radon — the highest classification. Mountain wells commonly test 1,000-5,000+ pCi/L. Radon in water off-gasses into your home every time you run a tap.

Arsenic

Rising in the San Luis Valley as aquifers deplete. 25% of tested private wells show elevated levels. Drought doubles or triples concentrations.

Aquifer Depletion

The Denver Basin is a finite resource. Water levels are declining 1-10 feet per year depending on the aquifer. Wells that produced 100 GPM now get 40.

The Exempt Well System

Most Colorado private wells are "exempt" — small-capacity wells with specific use restrictions. Properties under 35 acres can only use well water indoors. Know your permit.

Find Your Community

We've researched water quality conditions for communities across Colorado that rely on private wells. Each guide covers local geology, specific contaminants with real numbers, testing recommendations, and treatment options.