Who can make a difference?
- Rural landowners
- Semi-rural residential homeowners
- Businesses
Individual septic systems treat wastewater from homes and businesses in areas where there is no public sewer. Solids are removed from the wastewater in the septic tank, and then the remaining wastewater flows to the drainfield where it percolates into the soil. Natural biological and chemical actions in the soil remove most of the hazardous substances from the wastewater, but there are exceptions.
Failing septic systems don't treat wastewater adequately and can allow raw sewage to reach the ground surface.
Nitrate is not removed by the soil as the wastewater percolates downward. Ideally, septic systems should be spaced far enough apart that the nitrate simply is diluted by the great volume of groundwater under the acres of land surrounding the septic system. When there are many septic systems close together, however, there often isn't enough groundwater for dilution.
Current standards in Oregon require that wells be at least 50 feet from septic tanks and 100 feet from drainfields. Some older systems don't have adequate separation distance.
Causes of groundwater contamination
- Poor design or installation
- Failure to pump the tank on a regular schedule
- Damage to the drainfield
- Disposal of household chemicals, such as paint thinner, into the system
- Overloading the system by using a garbage disposal
- Too many people in the household for the size of the system
- Use of septic tank additives, drain cleaners, or lots of harsh household chemicals
- Too many closely spaced septic systems in a limited area
What can you do?
Individual action
- Pump your septic tank every 2-5 years depending on household and tank size.
- Install water-saving devices and reduce water usage in the home.
- Do not use septic system additives, garbage disposal, or harsh drain cleaners.
- Protect the drainfield area from damage by vehicles, heavy animals, or construction.
- Repair or upgrade your system if a need is indicated by inspection.
Community action
- Establish permit and inspection requirements to ensure proper installation.
- Educate the public about septic system care.
- Ban hazardous additives or cleaners for septic systems.
- Connect homes and businesses to central sewers when feasible.
- Require additional treatment, such as a sand filter, when needed.
- Establish ample minimum lot sizes for septic systems.
- Train and certify septic system professionals.
To learn more
Oregon Department of Environmental Quality On-site Sewage Treatment and Disposal Program
Michaek Kucinski
Phone: 541-440-3338 ext. 235
E-mail:
Kucinksi.Michael@deq.state.or.us
Or contact your county environmental health or planning department.
The source of information about regulations, permits, and licensing related to septic system installation and pumping in Oregon.
OSU Extension Service Well Water Program
- Home*A*Syst worksheets to help residents identify problems with septic systems
- Website has links to OSU Extension Service pubs and other info