Septic (OWTS) Rules in Arapahoe County, Colorado

A new regulation, and a licensing requirement that didn't exist under Tri-County

Arapahoe County Public Health's On-Site Wastewater Treatment System (OWTS) Regulation, adopted after a Board of Health hearing on March 18, 2026 and effective May 7, 2026, is the county's first standalone septic regulation since it became the sole remaining member -- and then the successor -- of the former Tri-County Health Department (shared historically with Adams and Douglas counties). The most consequential change for anyone in the septic trade locally: OWTS designers, soil evaluators, installers, inspectors, operation-and-maintenance providers, and pumpers are now required to hold a license from Arapahoe County Public Health and to carry certification from the National Association of Wastewater Technicians (NAWT).

For a land buyer, this matters two ways. First, if you're planning new construction on septic, confirm that whoever you hire to design or install the system actually holds the current county license and NAWT certification -- an installer who worked in the county under the old Tri-County rules isn't automatically licensed under the new regulation. Second, if you're evaluating an existing system, ask when it was last serviced and by whom, since documentation from a properly licensed provider will matter for any future permit or transfer action under the new rule.

Permits now run through an online portal, not paper applications to Tri-County

A septic permit is required for new installations, expansions, repairs, and continued use, and applications and fee payments now go through the county's online MyHD portal rather than a Tri-County-era paper process. Because the underlying regulation, the licensing scheme, and the application channel are all new as of 2026, treat any pre-2026 guidance about Arapahoe County septic permitting -- including older real estate or contractor checklists -- as outdated until you've confirmed current requirements directly with Arapahoe County Public Health.

Specific fee amounts were not published in a form independently confirmed during this review; the county's own fee schedule, referenced in the regulation and available through its Environmental Health office, is the authoritative source rather than a third-party estimate.

What this means for eastern-plains land around Byers and Deer Trail

Since almost all of Arapahoe County's rural, septic-dependent land sits in the eastern plains around Byers and Deer Trail, this regulation is the practical septic rulebook for that entire area -- there isn't a separate, less-regulated path for a rural parcel just because it's farther from Aurora or Centennial. If you're evaluating raw land there for a future home, budget for working with a properly licensed, NAWT-certified designer and installer from the start, since the county's new licensing requirement applies regardless of how rural the parcel is.