Douglas County septic permits and inspection rules

Permit requirements

Douglas County requires an OWTS permit for new installations, expansions, and most repairs. A complete application includes the permit fee, a system design, soils information with test pit logs and percolation tests where used, and a site plan. A licensed Colorado professional engineer must design systems on problematic soils, slopes over 20 percent, commercial sites, or pressure distribution.

What triggers an inspection

Selling the property is the biggest trigger: the seller must obtain a use permit before the sale, which requires a current inspection. New installations get a final inspection before the permit closes, and repairs or complaints can also trigger county review.

Transfer of title rules

The seller of a Douglas County property with a septic system is required to obtain a use permit prior to the sale. Plan for a licensed inspection and a tank pump-out ahead of closing, and build the processing time into the contract timeline.

Required pumping frequency

Douglas County recommends inspecting the septic tank every four years and pumping when scum and sludge exceed 25 percent of the tank's effective volume. For most households that works out to pumping every three to five years.

• Licensed systems cleaners should perform evaluations and pump-outs
• Keep receipts, they support the use permit at sale

Setback rules

Douglas County applies at least the Colorado Regulation 43 minimums: 100 feet from a well to the soil treatment area, 50 feet from a well to the tank, 50 feet from surface water, 10 feet from property lines, and 5 feet from a dwelling to the tank. Confirm site-specific setbacks with the county before excavation.

Soil and percolation testing

Permit applications must include soils information with test pit logs, plus percolation tests where that method is used. Expansive soils common in Douglas County often push designs to an engineered solution by a Colorado professional engineer.