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Sewage Treatment System Types

Learn more about the different types of sewage treatment systems and components at Information for Homeowners

Sewage Treatment Systems in an Emergency

Power Outages--Power Outages and Sewage Treatment Systems

Electrical power outages may affect the operation of your home sewage treatment system.  Sewage treatment systems operate either by gravity, or involve the use of pumps and valves that require electricity.  You will need to determine which type of system serves your home.


A gravity collection system feeding into a septic tank and gravity distribution into leaching trenches or the soil absorption area will continue to operate properly and you will be able to continue using your system.   You may use buckets of water (from a pond, stream or other similar source) to manually flush the toilet.

If your system contains components that require electricity to operate, the wastewater will collect in the septic tank, treatment unit or dosing tank during the electrical outage and will have to be treated and dispersed when electrical service resumes. Such components include:

Aerobic treatment units and recirculating media filters
Pump chambers to leaching (soil absorption) trenches
Sand filters
Dosing or flow equalization tanks
Low pressure distribution
Subsurface drip distribution

What can I do while the power is out?

Limit water usage to essentials such as toilet flushing and hand washing. Laundry, bathing, showers, and dishwashing should be minimized or eliminated during the power outage. Don't let the water run while brushing teeth, shaving or rinsing dishes.  Don't flush the toilet each time it's used for liquid waste.

The septic tank can hold about one-day's supply of waste. Once the tank is filled, additional waste can back up into your home.

Stop all water use if electrical outage is extended or the plumbing begins to drain slowly. Slow-draining plumbing may indicate that the reserve capacity in the tank is exceeded and the system is full.

If the system has a pump, turn off the pump at the control panel. Effluent (liquid sewage from the septic tank) will continue to build up in the pump chamber until it resumes operation.

CAUTION: Do not enter the pump chamber. Gases inside pump chambers are poisonous and the lack of oxygen can be fatal. Always turn off the power supply at the circuit breaker, and unplug all power cords before handling the pump or floats to prevent electric shock. The service or repair of pumps and other electrical equipment must be done by an experienced person.

What should I do once power is restored?

Contact your service provider or a licensed electrician if you are unsure or uncomfortable working with the components.  Your service provider will plug in any electrical equipment that was unplugged during the outage.  Always be careful when working with electrical components to prevent shock. 

If you have an operation manual for your system, refer to the manual for directions on restarting your system.

If your system is demand dosed (waste is pumped out to a treatment unit or soil as the tank becomes full), the pumping system can be manually operated to disperse the stored wastewater to the soil absorption field (leaching trenches). Manually operating the dosing system may be necessary to avoid overloading your soil absorption system following the first dose after the restoration of power.  Your system can be dosed manually by:

When the power is restored, turn the pump 'on' for 2 minutes and 'off' for 4 – 6 hours. You are now "dosing" the right amount of effluent into the drainfield over a given period of time. If there was little water use during the power outage, the pump may automatically turn off during the first manual dosing.

Conserve water and continue the 2-minute pumping every 4 – 6 hours until the pump turns itself off.

If your system is time dosed, allow the system to continue to operate normally until the water level reduced in the system. A pump system with a timer controls the number of times the pump starts and stops. It manages how much effluent (liquid sewage from the septic tank) goes into the soil absorption field (leaching trenches) in a 24-hour time period. Timers make sure that the soil absorption field only gets as much effluent as it was designed to handle. The timer system will eventually take care of itself once the power is restored. If the power has been off for awhile, the timer will be behind. In order to let your timer catch up, continue to conserve water for an additional day or more.

System components that require electricity are usually equipped with a high water alarm. This alarm may sound when the power is restored based on your water usage during the power outage. You can silence the alarm if it has a silence switch option. If the alarm remains activated more than 24 hours, contact your service provider.

Flood Events--When your septic systems is flooded

Heavy storms can cause flooding over portions of your sewage treatment system.  This factsheet is designed to provide information to assist homeowners who want to prepare for a possible flood and those who have experienced a flood event.

What can I do if I am in a flood prone area well in advance of a flood?

Have a licensed plumber install a backflow preventer on the building sewer so sewage cannot backup into your home during a flood. A backflow preventer is recommended as there is some concern a simple check valve may not close properly and sewage may back-up into the home. Make sure all inspection caps are in place. Threaded caps can be installed and the pipes can be cut flush with the ground.

What can I do immediately prior to a flooding event?

If the building sewer has a backflow preventer, nothing further needs to be done.If the backflow preventer is a manual valve, ensure it is shut.

It may be desirable to pump the tank to remove the sewage. Tank pumping immediately prior to flooding is not mandatory. If pumped, some sewage solids will remain in the tank and could mix with any floodwaters that enter the tank. It may be advantageous to block any lower level drains in the dwelling to prevent back up.

Make plans to minimize water use or flushing of toilets during the actual flooding event.

What should I do during the flood if the system is covered with water?

Do not use the system. Turn off water softeners to prevent them from regeneration.
Turn off the power to all the system’s electric devices (pumps, alarms, etc.). If you are using water from a flooded well, it may be contaminated. Contact a well professional or your county about a water test.

Once the flood waters receded, when can I use my system again?

Allow the soil to adequately dry to allow sewage to be absorbed and not back-up. This may take several weeks. You should try to conserve water until the system is completely dry.

All tanks should be checked to see if they contain floodwaters. If so, the tanks should be pumped to keep the silt particles from entering the soil system.

Effluent screens (if any) should be cleaned.

The electrical system (if any) should be inspected. This includes electrical connections, pumps, alarms, etc.

If your system has a pretreatment component, you should check with your licensed service provider before operation.

Any obvious damage should be repaired. All tank maintenance hole openings must be immediately secured, repaired, or replaced if the covers have been shifted, moved or lost in the flood.

How do I know if my system is damaged?

Signs of damage include: settling of soil over the tank or soil absorption system and/or the inability of the system to accept wastewater (indicated by sewage back-up or surfacing on the ground). If you observe either of the above after flood waters recede, contact your local health department

What should I do if sewage backs up into my home?

The Ohio Department of Health has developed a factsheet titled: When Sewage Backs Up Into Your Home.  The factsheet addresses the proper steps to consider while cleaning up after a sewage backup.

What concerns are there with home clean-up activities and my septic system?

The home cleaning process will likely result in the discharge of high amounts of disinfectants and cleaners into the septic tank. It is best to pump the tanks (a second time if floodwaters were previously pumped) to avoid discharging of these chemicals into the soil absorption component of the septic system.

Do not dump floodwaters that have entered the house into a plumbing fixture which discharges into the STS.

Do not drive vehicles and equipment over the system during clean-up or restoration activities.

Do not set dumpsters or building materials over the system. Fence-off the system to protect it.

What else should I look for after the flood?

Inspect the vegetation over your septic tank and soil absorption field.

Repair erosion damage and sod or reseed areas as necessary to provide proper cover.

What septic system work can I do myself?

Due to the many hazards in working with septic systems (disease transmission, poisonous gasses, and electrical shock) it is strongly recommended that all septic system work be conducted by a professional licensed as an STS installer or service provider.  Contact your local health department for a list of these individuals.  A licensed electrician should be contacted for any electrical work.

If these professionals have determined there is no damage to your system, a homeowner may re-sod or re-seed a damaged area.

US EPA General Operation and Maintenance Factsheets on Household Sewage Treatment System

Other General Operation and Maintenance Factsheets on Household Sewage Treatment Systems

Power Points and Training Webinars/Videos

2019 Midwest Power point presentations

On-lot Septic Field Limiting Conditions: What are they, where are they found, and why do they matter?

Designs, As-builds and other reporting requirements 

2018 Midwest Power point presentations

Operation and Maintenance Tracking Program

Sewage Treatment Sewage Program Survey

To connect to the Archives of the recorded webinars click on each link. 

 2015 Archived Presentations:

Sophie O'Connor RS  Operation and Maintenance Tracking Program in Darke County
Andrew Thomas RS A Guide to Trench System Calculations
Matt Deaton Soil Scientist-- From Soils Report to Design
Delaware County-- Steps for Mound Review
Ron McAdams--StreamKey--Steps to review a Drip Distribution System
Dr Larry Brown OSU Using DrainMod Model Results  to Evaluate Engineered Drai Designsnage

    Septage Management Workshop 
Rebecca Fugitt RS--New Statewide Sewage Rules
Tom Frank--Septage: What is it and What are my options for Disposal and Reuse
John Colletti--US EPA Region 5--Domestic Septage and 40 CFR Part 503
Betsy Vanwormer--Ohio EPA--Biosolids: An Overview
Dan Leavitt--Dos and Don'ts for Bringing Septage to a Wastewater Plant
Mark Fritz-- Agronomic Benefits of Land Applications 

Law and Rules

As of January 1, 2015 new law and rules went into effect that govern Sewage Treatment Systems (STS) and Small Flow On-Site Sewage Treatment System (SFOSTS)  

The law is found in Ohio Revised Code Chapter 3718 

The rules are found in Ohio Administrative Code Chapter 3701-29

National Pollutant Discharge Elimination (NPDES) Permit

ORC Chapter 3718 requires compliance with NPDES permit requirements for new and replacement discharging HSTS. An installation permit for a new (limited conditions) or replacement discharging HSTS cannot be issued by a local health district until a homeowner obtains NPDES permit coverage from Ohio EPA. For more information, visit the NPDES Overview Page.

Small Flow On-site Sewage Treatment Systems (SFOSTS)

The small flow on-site sewage treatment system (SFOSTS) is a new category of sewage treatment system (STS) established by Chapter 3718 of the Ohio Revised Code.  Under the provisions of this law and rule of the Ohio Administrative Code (OAC) Chapter 3701-29, local boards of health may choose to assume authority for SFOSTS and in doing so must regulate SFOSTS permitted under their authority in accordance with the STS rules (OAC Chapter 3701-29) governing both household sewage treatment systems (HSTS) and SFOSTS. 

SFOSTS – Change of Authority Issues:

In jurisdictions where a local board of health does not assume SFOSTS authority, the Ohio Environmental Protection Agency (OEPA) will continue to have authority for these systems as well as all other wastewater systems except HSTS.  The following links provides information on the transition of authority from OEPA in cases where SFOSTS authority is assumed by local boards of health.  The SFOSTS Design flow work sheet is also provided.

SFOSTS Design Flow and Waste Strength-Table A-1

List of local health districts that have SFOSTS authority

(RRRR) Definition of SFOSTS – OAC Rule 3701-29-01 

“Small flow on-site sewage treatment system” or “SFOSTS” means a system, other than a household sewage treatment system that treats not more than one thousand gallons of sewage per day and that does not require a national pollutant discharge elimination system permit issued under section 6111.03 of the Revised Code or an injection well drilling or operating permit issued under section 6111.043 of the Revised Code. For the purposes of this chapter, structures that are served by a small flow on-site sewage treatment system shall also include:

  1. More than one dwelling or arrangements such as a dwelling and a detached garage with living space.
  2. More than one vacation rental cabin.
  3. A dwelling and related structure, such as a barn or personal garage, when the structure is used by persons other than, or in addition to the residents of the dwelling.
  4. A dwelling with a home business when the nature of the home business is such that it produces sewage, including but not limited to, home businesses that provide a public restroom for use by nonresidents.

Sewage Treatment System Technical Advisory Committee

The Sewage Treatment System Technical Advisory Committee (TAC) was established in 2004 under section 3718.03 of the Ohio Revised Code (ORC).  The TAC's mission is to assist the Ohio Department of Health (ODH) in the review and approval/disapproval of sewage treatment systems (STS) and components that differ in design and function from those authorized for use in the sewage treatment system rules (Ohio Administrative Code 3701-29).  Specifically, ORC Section 3718.03 states that the TAC is to:

  • Work with ODH to develop an application and standards, guidelines and protocols for ORC Section 3718.04 review.
  • Review applications as specified in ORC Section 3718.04
  • Review and recommend approval or disapproval of the request to the Director of Health.
  • Actively pursue and recruit the research, development, introduction, and timely approval of innovative and cost-effective household STS and components including conducting pilot projects to assess the effectiveness of the STS component.

Ohio Revised Code 3718.03

Ohio Revised Code 3718.04

Fact sheets and Reports

2012 Report on Household Sewage Treatment System Failure Rates in Ohio