Household Sewage Treatment Systems & Power Outages

For those who live or work in the unsewered areas of Hamilton County, wastewater from their homes or businesses are treated by a sewage treatment system. There are two different main types of systems, nonmechanical and mechanical. The first does not utilize electricity in the wastewater treatment process and operates solely by gravity. Systems such as gravity leach lines, sand filters or drywells fall into this category. There are really no worries with these types of systems during a power outage.

The second type of system uses electricity to run a motor (aerator or pump) to treat or move the wastewater. Aerobic treatment units (ATU) are mechanical systems and come in many shapes, sizes, and are sold under different brand names. The principle operation is basically the same, however — air injected into sewage by an aerator provides agitation and oxygen that allows bacteria to reduce organic waste to carbon dioxide and water. Pumped systems such as dosed leach lines, mounds, intermittent sand filters or AdvanTex differ by allowing wastewater to build up in a dosing tank or chamber before moving it to the next system component for treatment.

Aerobic treatment units will discharge untreated wastewater if used heavily or for extended periods during a power outage. Pumped systems may back up into the house or yard if used excessively during a power outage. Therefore, during these conditions, precaution must be taken if your property uses a mechanical sewage treatment system.


What should I do when the power goes out?

  • Aeration Treatment Units
    Conserve water until power comes back on.
  • Pumped Systems
    Conserve water. You may also want to check the water level in the dosage tank/chamber to be aware of the capacity left before a backup occurs.


What should I do when the power comes back on?

Continue to conserve water for several hours to allow your system to catch-up on treatment. Immediately check the electrical components of your sewage system to make sure all parts are working properly. Also check circuit breakers to make sure there are no tripped circuits. Alarms may sound during this time period which could continue for several hours, even if reset. Continue to monitor the system for the next several days to verify proper operation and treatment. If you suspect a problem with your system at any time, contact a registered and qualified service provider to troubleshoot and repair it.



For more information, contact the Water Quality Division at 513.946.7872 or visit


Download a printable version of this fact sheet here.


250 William Howard Taft Road
2nd Floor, Cincinnati, OH 45219
Phone 513.946.7800 Fax 513.946.7890