Subsurface Sewage Treatment System (SSTS / ISTS)

What is an SSTS?
A Subsurface Sewage Treatment System (SSTS) is a system that treats wastewater for one specific residence.  Wastewater includes all bathroom, kitchen, and laundry water.  Proper treatment reduces health risks to humans and animals and prevents surface and groundwater contamination.

An SSTS permit is required whenever a sewage treatment system in Renville County is installed, replaced, altered, repaired (with some exceptions), or extended.

A septic system that fails to treat sewage can:
Allow disease-causing viruses to enter groundwater; raise nitrate levels in groundwater, which is harmful to infants; attract excess flies and mosquitoes to the area; lead to algal blooms in nearby ditches, creeks, rivers, or lakes; and introduce synthetic cleaning compounds that can be toxic to animals and humans.


What are components of an SSTS?
The complete system is made up of three primary components:

  • Plumbing:  wastewater collection.  All water used in bathing, toilets, laundry, and dishwashing must be delivered to the septic tank via pipes.
  • Septic tank:  primary treatment.  Naturally occurring bacteria in the sewage begin to break down materials in the tank.  Pathogens in the waste are NOT destroyed in the septic tank.
  • Soil treatment:  final treatment.  Soil treatment kills disease-causing organisms in the sewage and removes nutrients.  This portion of the system would consist of treatment options such as a rock-filled or gravelless pipe trench, pressure bed, or mound.

How would I know if my septic system is failing or non-compliant?
A properly functioning septic system is designed to treat the wastewater from your home to reduce potential health risks to people and to prevent surface and groundwater contamination.  Does your septic system:

  • Discharge into a tile line, drainage ditch, or other waters?
  • Discharge to the ground surface?
  • Occasionally back up into your home?

If so, then your system would be considered failing or non-conforming.

How do I upgrade or install an SSTS?
MN Rules Ch. 7080-7083 and the Renville County Sewage and Wastewater Treatment Regulations regulate the design and installation of a septic system.  The septic design/application takes into consideration characteristics specific to your site including soil type, size of the house, and wastewater-contributing appliances.  The first step to upgrade or install a new system is to contact a licensed septic designer.  The system must be designed and installed by a licensed septic contractor.  For a list of licensed septic designers and installers, contact the Renville County Environmental Services or visit the MN Pollution Control Agency (MPCA) website.

How do I maintain my SSTS?
The septic tank MUST be periodically cleaned (pumped) to remove accumulated solids.  If solids are not occasionally removed, they may enter the soil treatment system and cause expensive damage or cause sewage to back up into your home.  State rules require that septic tanks be pumped a minimum of once every three years.  For a list of licensed septic pumpers, contact the Renville County  Environmental Services or visit the MN Pollution Control Agency (MPCA) website.

For new installation, the tank should be cleaned after six to 12 months of use as a precautionary measure to ensure good bacterial activity and proper functioning.  Once a system is known to be operating properly, the University of Minnesota provides a worksheet that can be used as a guideline for cleaning frequency.  Remember, maintenance of the septic system is the homeowner’s responsibility.

Is there assistance available for SSTS upgrade?
Renville County Water and HHW Management (320-523-3706) administers a low-interest loan program funded through the MN Department of Agriculture.  For more information, please click here.  The loan is only available for eligible activities.

Eligible expenses include:
All expenses associated with the repair or replacement of an existing septic system that would be considered failing or non-conforming according to provisions of MN Rules Ch. 7080-7083 are eligible for loan proceeds.  Eligible expenses could include septic design fees, permit fees, electrical wiring of pumps or alarms, and general installation costs.

Ineligible expenses:
Installation of septic systems for new construction.  Expansion or upgrading of a conforming septic system due to construction of additional living space, new construction, or expanded use of the system.  Costs incurred before loan approval and the effective date of the loan agreement.

Renville County occasionally participates in other low-interest loan and grant programs as funds become available.  Contact the Water and HHW Management office (320-523-3706) for additional funding opportunities that may be available.

Where can I find additional information on septic systems?
For more information on septic systems visit the following websites:

  • University of Minnesota Extension Service
  • Minnesota Pollution Control Agency (MPCA):  SSTS Rules, Laws and Statutes, Regulations

Or contact:  Renville County Environmental Services, 105 South 5th Street, Suite 311, Olivia, MN 56277,  (320) 523-3768.