DEQ's Onsite Wastewater Management Program regulates the siting, design, installation, and ongoing operation and maintenance of septic systems. This oversight helps prevent septic system failures, which can release untreated sewage onto land, into groundwater and waterways and create public health risks.
In areas where a municipal sewer system is not available, development must use onsite wastewater treatment systems, or septic systems, for sanitary disposal. A basic septic system includes a septic tank where solids settle and break down and fats, oils, and greases float. Between these two layers is the “clear zone" septic tank liquid that discharges to a drainfield to be treated by bacteria in the soil. More complex septic systems are installed in areas with high groundwater and/or poor soils. Examples include sand filter or alternative treatment technology systems, which treat the wastewater to a higher level prior to discharge to a drainfield or other soil absorption area.
A well-functioning septic system protects groundwater and surface water. A failing system can harm human health and damage natural resources. Not every property is suitable for a septic system. There must be sufficient usable space for an initial septic system and a replacement septic system that can accommodate proposed sewage flows and meet necessary setbacks to public waters, wells, and other development. Small lots with high density development proposals may not be possible if public sanitary sewer is not available. Any size lot with a shallow water table or challenging soil conditions, such as compacted fill or a shallow restrictive layer, may also be unsuitable for a septic system.
Process overview
There are two types of permits for facilities that use septic systems to manage their domestic wastewater disposal needs.
- Construction permit: This includes permits for new construction and for alterations and repairs of existing septic systems. They are valid for up to one year and, in many areas of the state, are issued by a local agent of DEQ, typically a county.
- Water Pollution Control Facilities (WPCF) permit: This is an operating permit and is required to construct and operate a system. They are issued for up to 10 years and must be renewed for the life of the system. This permit has compliance limits for sewage flow and waste strength and often requires ongoing monitoring and reporting to DEQ. There are also specific requirements for who may design, inspect, and finalize the system.
A site evaluation is required if you are building on an undeveloped site that has never been evaluated for septic system approval and may be required if you want to replace an old system with a new system at a different location on the property. A site evaluation approves a site for the type and quantity of waste to be disposed.
While you do not need a Land Use Compatibility Statement before applying for a site evaluation, an affirmative LUCS is required before DEQ will issue a construction permit for new construction and alterations of existing septic systems.
Key takeaways
Septic systems can be a safe wastewater solution for certain properties with careful planning and development that do not have public sanitary sewer legally and physically available.
Some sites may not be suitable for a septic system, if they lack:
- Sufficient usable space
- Ability to meet required setbacks
- Capacity for proposed sewage flows
- Appropriate soil conditions or water table depth
When to contact DEQ
External housing production partners should speak with the local Onsite program when public sanitary sewer is not legally or physically available to a property and a septic system is needed. Contact the local Onsite program or local government as soon as you know a septic system may be required.