OAR 918-770-0080
Construction and Installation of Composting Toilets


Definition: “Compost toilet” means a permanent toilet receptacle used to receive and store human wastes, toilet paper, biodegradable domestic garbage, and other vegetative matter for the purpose of aerobic decomposition of materials received therein.


Product and Design Approval:


Before a manufactured or individually designed compost toilet is installed, approval must be obtained from the division with concurrence of the board by an approved certifier to the approved standards in OAR 918-770-0050 (Purpose) to 918-770-0320 (Approved Plumbing Product Standards and Specifications);


Criteria used to evaluate the units includes, but is not limited to:


NSF Standard 41 (May 1983 revised); or


Composting toilets listed by NSF International to NSF Standard 41 (May 1983 revised) are approved.


Site Locations: Residential compost toilet installations shall be limited to areas where a grey water disposal system approved by the Department of Environmental Quality can be installed and used; or such grey water is discharged into a public sewage system.




Prior to commencement of the installation of a composting toilet, a plumbing permit must be obtained from the authority having jurisdiction. A permit will be granted upon showing:


The site location is in accordance with these rules; and


The manufactured composting toilet or individual design has been approved by the division or listed with NSF International to Standard 41 (May 1983 revised).


Compost toilets shall be designed to provide a solid connection to the floor with corrosive-resistant fasteners:


All suspended under-floor components shall be supported with non-corrosive hangers adequately designed to support the weight of the system. Hangers shall meet the approval of the authority having jurisdiction;


All under-floor components designed to set on a stable surface shall have footings adequately designed to support the weight of the system.


Vent pipes shall be sealed at all joints and insulated in a way to minimize condensation. The vent stack shall be insulated in a way to minimize condensation. The vent stack shall extend from each chamber or seat box to a point at least two feet above the highest elevation of any portion of the building within ten feet of the vent. Each vent shall be flashed and shall terminate not less than ten feet from or at least three feet above any window, door, opening, air intake, or vent shaft; nor less than three feet in every direction from any lot line, alleys and streets excepted;


All compost toilets shall be installed in an insulated area, or the chamber shall be insulated to maintain a proper temperature inside the chamber to keep a biological balance of the materials therein;


Where a compost toilet is installed in an existing dwelling, piping, fixtures or equipment shall be located to not interfere with normal use or normal operation and use of windows, doors, or other required facilities.




All installations shall be installed in a workmanship like manner and shall not be put into use until inspected and approved by the authority having jurisdiction;


Either the authority having jurisdiction or the division may conduct periodic inspections of any compost toilet in accordance with ORS 447.124 (Inspection of compost toilets).




Humus from composting toilets may be used around ornamental shrubs, flowers, trees, or fruit trees and shall be buried under at least twelve inches of soil cover. Deposit of humus from any compost toilet around any edible vegetable or vegetation shall be prohibited;


The compost toilet system of any premises under the jurisdiction of the authority having jurisdiction shall be maintained in a sanitary and safe operation condition by the owner or by his agent. Whenever compliance with all of the provisions of these rules fails to eliminate or alleviate a nuisance or any dangerous or insanitary condition which may involve health hazards or safety hazards, the owner or the owner’s agent shall install such additional plumbing and drainage facilities or shall make such repairs or alterations or removals as may be ordered by the authority having jurisdiction.
[Publications: Publications referenced are available from the agency.]

Source: Rule 918-770-0080 — Construction and Installation of Composting Toilets, https://secure.­sos.­state.­or.­us/oard/view.­action?ruleNumber=918-770-0080.

Last Updated

Jun. 8, 2021

Rule 918-770-0080’s source at or​.us