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Regulatory Updates

CPOW has been working with key stakeholders and the Colorado Department of Public Health and the Environment (CDPHE) to address the key recommendations of the ISDS Steering Committee which was established in 2002 by CDPHE. In addition to the Steering Committee’s key recommendations, CPOW introduced a bill in 2012 that updated the language in the state statute for onsite wastewater treatment systems. CPOW continues to work toward advancing the onsite wastewater treatment system industry and is involved in the current stakeholder group for revision of Regulation 43. In an effort to keep the profession informed on legislative changes, we have included summaries on our Regulatory Updates page.

Regulatory Updates

CDPHE Clean Water: On-site Wastewater Treatment Systems

JUNE 2025 UPDATE:

The updated regulation was adopted March 2025, and was posted to the CPDHE website effective June 15, 2025. County Health Departments across the state will have one year to submit any additional changes or updates to their OWTS program rules and requirements.

UPDATED REGULATION 43

Under the OWTS Act, Colorado implements Regulation 43, which governs on-site wastewater treatment systems, or septic systems. Regulation 43 sets minimum standards for how small wastewater treatment systems in Colorado (treating 2,000 gallons of wastewater or less per day) should be sited, designed, constructed, and used. County health departments use these minimum standards to create rules, including permit application requirements, issuing permits, system inspection, and system maintenance.

Starting in August 2023, the Water Quality Control Division held meetings to discuss possible changes to Regulation 43. The division considered the following changes to the regulation:

  • Updating references to the most recent versions of technical standards.
  • Clarify various sections to state the legal intent more clearly.
  • Correcting current cross-referencing errors.
  • Clarifying general prohibitions and permitting requirements.
  • Expanding or clarifying requirements for flow estimates and required setbacks.
  • Updating and/or defining OWTS design requirements.
  • Clarifying perceived conflicts within the regulation.
  • Updating when higher-level treatment systems are necessary for high-risk areas.

County Regulation Contacts

Below is a list of contacts at the various City, County and State Health Departments. When possible, we have provided a link to the county website, along with the program lead’s name and phone number for OWTS questions or issues. General numbers are listed if the contact is not known.

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