The activities of the On-Site Sewage Program are governed by the Washington State and Mason County Codes and Regulations.  For more information, click on the following links.

Mason County On-Site Regulations & Standards

• Mason County On-site Regulations (Effective Jan. 1st, 2022)
• Mason County On-Site Standards (Effective Jan. 1st, 2022)
• Mason County Environmental Health Building Permit Policies (Effective Jan. 24th, 2023)
• Mason County Basic Sanitation Policy

Washington Administrative Code (WAC)

• Chapter 246-272A WAC, On-site Sewage Systems
• Chapter 246-272C WAC, On-site Sewage System Tanks
• Chapter 246-273 WAC, On-site Sewage System Additives

Revised Code of Washington (RCW)

• Chapter 43.20.050 RCW, State Board of Health-Delegation of Authority
• Chapter 43.70.310 RCW, Cooperation with Department of Ecology
• Chapter 70.118 RCW, On-site Sewage Disposal Systems
• Chapter 70.118A RCW, On-site Sewage Disposal Systems - Marine Recovery

Recommended Standards and Guidance Documents and other Technical Information

• Wastewater Management Publications