At a glance
| Who regulates | Your county or local public health agency, under Regulation 43 (5 CCR 1002-43) |
|---|---|
| Inspection when a home is sold | Required in some areas. Depends on the county: 22 counties required a transfer-of-title inspection as of early 2026. El Paso County dropped its requirement on July 11, 2026. Ask your county. |
Septic tank size in Colorado
Set by Regulation 43 and your county's rules, which can be stricter. Ask the county health department for the minimum for your home.
Compare with other states on our tank size calculator.
State and county rules
- Regulation 43 sets minimum standards for design, installation and alteration statewide.
- Counties can add stricter rules, and many older grandfathered systems now need inspection or upgrades in some counties.
- The state's standard real estate contract requires sellers to disclose known problems, including with the septic system.
Costs
We don't yet have checked Colorado-specific prices. National figures: pumping averages about $420–$430 (pumping cost), inspections about $550 on average (inspection cost), and a conventional system $3,000–$8,500 installed (installation cost).
Rules change, and counties and towns can be stricter than the state. Confirm with the agency above before you buy, sell or build.