Plain-language definitions of the septic and Oregon regulatory terms you will see across this site. Rule citations are to OAR chapter 340, divisions 071 and 073 as rewritten effective January 1, 2026. Last updated August 2026.
Agent: The body that runs the onsite septic program where your property sits. OAR 340-071-0100 defines an agent as the director or a person authorized to act on the Director's behalf, and notes it frequently refers to DEQ or contract county staff performing onsite permitting activities. Because the technical rules are statewide, the agent is the desk you deal with rather than a different set of rules.
Alternative Treatment Technology (ATT): A treatment unit that goes beyond a conventional septic tank, usually to cut nitrogen, before effluent reaches the soil. Under OAR 340-071-0132 every ATT system must be under a maintenance contract regardless of when it was installed — there is no grandfather date for this class.
Annual Report Evaluation Fee: The charge for reviewing the yearly maintenance report on a system that must carry a service contract. OAR 340-071-0132(4)(a) places it on the maintenance provider rather than the owner, so it usually reaches you inside the price of the contract instead of as a separate government bill. The DEQ surcharge does not apply to it.
Baffle: A barrier inside the septic tank that controls flow between compartments and keeps solids from migrating toward the drainfield.
Certified Maintenance Provider: A person certified by DEQ to inspect, service and report on systems that require a service contract. Who holds the certification matters in Oregon: some work is permit-exempt only when a certified provider or certified installer performs it.
Contract County: A local government that has entered into an agreement with DEQ under OAR 340-071-0120 to perform DEQ's duties under the onsite rules. Thirty-three of Oregon's thirty-six counties are contract counties.
DEQ: The Oregon Department of Environmental Quality, which writes the statewide onsite rules and issues residential permits directly in Curry, Jackson and Josephine counties, out of its Medford office. DEQ's regional office map is not the septic service map: Lane, Douglas and Marion sit inside DEQ's Western Region but are contract counties, so their septic permits do not come from DEQ.
DEQ Surcharge: A flat state charge added to each site evaluation, permit and similar application on top of whatever the county charges. OAR 340-071-0140(10)(a) requires DEQ and contract counties to levy it. It was $100 from July 1, 2021 and $117 from August 1, 2024; county fee schedules effective July 1, 2026 show $159. It does not apply to pumper truck inspections, annual report evaluation fees, or certification of installers and maintenance providers.
Drainfield (Soil Absorption Facility): The buried network of trenches or beds where effluent leaves the pipes and the soil finishes treating it. Oregon's rules call it the soil absorption facility, and that name matters: replacing it is a major repair, while replacing the tank is only a minor one.
Effluent: The liquid that leaves the septic tank once solids have settled and grease has floated. It is partly treated, not clean; the soil does the rest of the work.
Failing System: OAR 340-071-0100 defines it as any system that discharges untreated or incompletely treated sewage or septic tank effluent directly or indirectly onto the ground surface or into public waters, or that creates a public health hazard. Oregon gives no list of examples and nothing has to be visible on the surface. See Public Health Hazard.
Groundwater Management Area (GWMA): An area declared under ORS 468B.175 to 468B.188 where groundwater contamination has reached a set level. Oregon has exactly three: Northern Malheur (1989), Lower Umatilla Basin (1990) and the Southern Willamette Valley (May 10, 2004). Living inside one does not by itself place any duty on a septic system owner, which is a common misreading. Groundwater limited area and geographic area of special concern are not Oregon terms.
Jointly and Severally Responsible: The phrasing OAR 340-071-0120(2) uses for the owner's duty to treat wastewater generated on the property and to maintain, repair and replace the system. It attaches to ownership of the real property rather than to whoever installed or broke the system, so a buyer takes it on at closing, and where a property has several owners each one is answerable for all of it.
Major Maintenance: Work such as repairing or replacing a broken distribution box or drop box, or a broken or plugged effluent sewer pipe. Under the rules effective January 1, 2026 this is permit-exempt when a certified installer or certified maintenance provider performs it. The identical job done by the property owner still needs a permit — the exemption attaches to who does the work, not to what the work is.
Major Repair: Replacing the soil absorption facility, the treatment unit, or any part of either.
Minor Repair: Replacing a septic tank, broken pipe, distribution unit, or any part of the onsite system outside the septic tank or treatment facility, except the soil absorption system. Replacing the whole tank is therefore a minor repair, which is the opposite of what the cost suggests.
Notice of Noncompliance: The written notice an agent must issue if it allows repair of a failing system to be delayed because soil conditions from the weather would likely defeat the repair. OAR 340-071-0215(1) requires the notice to set a compliance date and any interim provisions. A homeowner who decides to wait for spring without one is simply out of compliance.
OAR Chapter 340, Divisions 071 and 073: Oregon's statewide onsite wastewater rules. The Environmental Quality Commission adopted the first substantial rewrite since 2014 on September 11, 2025, effective January 1, 2026. Paragraph numbers moved in that rewrite, so older articles — and some documents still posted by agencies — cite subsection numbers that no longer line up with the current text.
Onsite Wastewater Treatment System: Oregon's formal name for what most people call a septic system: everything that treats and disposes of sewage on the property where it is generated instead of piping it to a municipal sewer.
ORS 105.464: The statutory Seller's Property Disclosure Statement. Section 3 is headed Sewage System and carries fourteen septic questions, among them whether the system was installed by permit, whether its condition has been evaluated and a report issued, and whether all components are located on the property. Oregon does not require a septic inspection when you sell — it requires you to answer, on a statutory form, whether one was ever done.
Pressurized Distribution: A system that pumps effluent through small-diameter pipes to dose the drainfield evenly rather than letting it run out by gravity. Under OAR 340-071-0132 a pressurized distribution system permitted after January 1, 2014 must carry a maintenance contract; an otherwise identical one permitted before that date need not.
Public Health Hazard: Defined in OAR 340-071-0100 as the presence of sufficient types or amounts of biological, chemical, physical or radiological agents relating to water or sewage that cause, or threaten to cause, human illness, disorders or disability. The words threaten to cause are what make Oregon's failure definition so wide: a threat is enough, with no pooling, odor or backup required.
Recirculating Gravel Filter: A treatment unit that passes effluent through a gravel bed repeatedly before it reaches the drainfield. Like ATT systems, every recirculating gravel filter must be under a maintenance contract no matter when it was installed.
Repair Permit: Required before repairing a failing system under OAR 340-071-0215(2). The exception is emergency repairs, which may be started first provided the permit application reaches the agent within three working days of the work beginning.
Riser: A vertical shaft that brings a tank lid up to or near ground level so the tank can be pumped and inspected without digging.
Sand Filter: A treatment unit that filters effluent through sand before it reaches the drainfield. Whether it must carry a maintenance contract turns on dates: residential sand filters permitted after January 1, 2014, and commercial sand filters on or after March 1, 2005, are covered.
Service Contract: The maintenance contract OAR 340-071-0132 requires for certain system types. It must be perpetual and continuous, and the system must be inspected and serviced at least once every 12 months. There is no allowance for a gap while you shop for a new provider.
Setback: The minimum distance required between a septic component and a well, water line, property line, cut bank or body of water. A footnote to the setback table provides that a well built to Water Resources Department special standards drops the required drainfield separation from 100 feet to 50 feet.
Site Evaluation: The soil and site assessment that must pass before a permit can be issued. ORS 454.755(2) provides that the fee entitles the applicant to as many site inspections as are necessary within 90 days of the first one — so a homeowner whose site fails has already paid for the re-inspections.
A note on sourcing: the rules were substantially rewritten effective January 1, 2026 and paragraph numbers moved. We read OAR 340-071-0215 (repair timing) and the setback table footnote from an archived copy of the rules and have not yet confirmed the paragraph numbering against the current published text. The substance is consistent across the sources we checked; the number may have shifted.
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