The Environmental Quality Commission adopts rules for connecting ADUs to septic, other onsite updates

The Environmental Quality Commission, the governing body for the Oregon Department of Environmental Quality, in September adopted updated onsite septic rules. These changes address accessory dwelling units (ADUs) and sewer availability.

The EQC unanimously approved the updates, with a 3-0 vote, during its regular meeting on Sept. 11, 2025, at Southern Oregon University in Ashland. The rule changes address issues from the 2023 legislative session related to ADUs and sewer availability through senate bills 835 and 931.

In addition to ADUs and sewer availability, the updates cover variance processes, nutrient and nitrate loading considerations, requirements for septic system operation and maintenance, and general housekeeping items. The last substantial onsite program rule changes had occurred in 2014.

Following the recommendation of DEQ onsite septic staff, the EQC also clarified existing rules by using simpler language, removing outdated terms, and aligning with industry standards. Nutrient and nitrate loading updates add more protection for public health and the environment. The updated rules do not increase fees and will take effect on Jan. 1, 2026.

For more information

See all materials presented to the commission on the DEQ website. To get the latest updates on the Onsite (Septic) Sewage Systems sign up for our email list through GovDelivery.