Colorado county well guide

Well Water in Boulder County, CO: Testing, Contractors and Rules

About 125,780 households in Boulder County, 99% of the county, rely on a private well. Nobody tests that water unless the owner does.

Labs within 40 milesLicensed contractors
99%of households on a private well
Share on wells, county vs state
Boulder County99%
Colorado average11%
11licensed contractors serve the county
17 mito the nearest certified lab, Murray-Brown Laboratories, LLC.
Nostatewide test required when a home is sold

In Boulder County, roughly 99% of households, about 125,780 homes, draw their water from a private well. Nobody tests it, treats it or inspects it unless the owner does.

Local rules for wells in Boulder County

Every well in Boulder County needs a permit from the Colorado Division of Water Resources before drilling, and only licensed contractors may drill or set the pump. Water quality is not regulated for private wells, so testing is entirely the owner’s call.

At a glance

Water test for a new wellNot required statewide

A DWR well permit is required before drilling and contractors must notify DWR before construction, but no water quality test is required by the state.

Water test when a home is soldNot required statewide

No statewide requirement. Lenders often require a test; some counties recommend one at transfer.

What the state recommends

CDPHE recommends yearly testing for coliform bacteria and nitrate, and a broader panel (metals, uranium, radon, fluoride, hardness) every few years. Colorado groundwater commonly has naturally occurring uranium, radon and fluoride.

Free or low-cost testingAvailable

Colorado offers a free PFAS testing program for private wells. Several county health departments (Weld, El Paso, La Plata, Mesa, Pueblo, Routt, Gilpin, Northeast Colorado) run certified labs that accept homeowner samples.

Getting your water tested near Boulder County

The nearest certified lab is Colorado Analytical Laboratory – Commerce City in Commerce City, about 19 miles from the county center, and it accepts samples from homeowners. There are 14 more within 40 miles, listed below with what each tests for.

16 certified labs within 40 miles

Licensed well contractors serving Boulder County

Licensed help in Boulder County includes Avco Ventures Inc. and Boulder Water Well Service & Supply and 9 others. Every listing was matched to the Colorado license list; the “verify” link on each profile opens the state lookup.

Well depth and water chemistry

Well depth and water chemistry in Boulder County follow the rock underneath it. Depth varies across the county; the state well record search shows logs for nearby wells.

Typical well depth

Varies by location. Check the state well record search for logs of nearby wells.

Contaminants to test for
  • Uranium
  • Radon
  • Fluoride
  • Nitrate
  • Hardness
  • Coliform bacteria
  • Arsenic (some basins)

Neighboring counties: Broomfield County, Adams County, Gilpin County, Jefferson County.

What well work costs in Boulder County

Basic bacteria and nitrate test$25 to $75lab fee, homeowner sample
Full panel lab test$150 to $400metals, VOCs, radiologicals
Well inspection$250 to $550flow, pressure, visual, water test
Submersible pump replacement$1,200 to $4,500parts and labor
Pressure tank replacement$400 to $1,200installed
Whole-house treatment system$800 to $6,000softener, iron filter, UV, RO
New well drilled$5,500 to $25,000about $25 to $65 per foot
Shock chlorination$80 to $300or about $20 as a DIY job

National ranges from published 2025 to 2026 contractor pricing. Local quotes vary with depth, access and materials.

Questions Boulder County well owners ask

How many homes in Boulder County are on a well?

About 125,780, or 99% of households, based on Census housing data and state well surveys. The share is highest outside the towns with public water.

Where is the closest certified lab to Boulder County?

Colorado Analytical Laboratory – Commerce City in Commerce City, about 19 miles away. It accepts homeowner samples.

Do I need a permit to drill a well in Boulder County?

Yes. A permit from the Colorado Division of Water Resources is required before any drilling.

What does a well test cost near Boulder County?

A bacteria and nitrate test runs $25 to $75 at most certified labs; a full panel with metals is $150 to $400. County health department labs charge less than commercial labs, and PFAS testing is free through the state.