Septic System Information

If you're thinking of inspecting your own sewage treatment system (STS) starting in 2020 it's a good idea to do your homework on how your STS should be functioning. 
COMING SOON we will have information on each of the following sewage treatment systems and some common issues users of each of these systems experience.

In the meantime, take a look at the OSU extension office's septic system maintenance page here.

Treatment and Pretreatment Types

Septic Tanks

Septic tanks help keep solid waste from clogging the rest of the system. When maintained correctly, solid waste will sink to the bottom of the tank allowing the rest of the sewage to move on the the next part of treatment. Septic tanks have evolved over the years to have more ways to keep solids from causing damage to the septic system.  In the pictures below you will see a cross section of a septic tank. You'll see the sludge layer (solids) at the bottom and a scum layer (Oils and other fluids lighter then water) at the top. It is important to regularly pump out your septic tank in order to make sure that sludge and scum layers don't build up and cause irreversible damage to the system.

How often you should pump your tank is different for each system. It depends on how many people live in your home and the size of your septic tank.Below is table created by The Ohio State University that determines how often you should get your tank pumped based on those two factors.


Table 1. Estimated septic tank pumping frequency (in years) for different size tanks for 1 to 9 people in a household of year-round residence.
Note: If a garbage disposal is used, more frequent pumping is required. 
Tank Size
(in gallons)
Number of People
1 2 3 4 5 6 7 8 9
500 5.8 2.6 1.5 1 0.7 0.4 0.3 0.2 0.1
750 9.1 4.2 2.6 1.8 1.3 1 0.7 0.6 0.4
1,000 12.4 5.9 3.7 2.6 2.0 1.5 1.2 1 0.8
1,500 18.9 9.1 5.9 4.2 3.3 2.6 2.1 1.8 1.5
2,000 25.4 12.4 8 5.9 4.5 3.7 3.1 2.6 2.2
2,500 31.9 15.6 10.2 7.5 5.9 4.8 4.4 4 3.0

Leach Field

One of the most common treatment types is a leach field. Leach fields start with a diversion box which diverts sewage into several long leach lines that allow sewage to trickle through the ground water without discharging to the surface. It relies on the microbes naturally present in the soil to clean the sewage before it is reused. Leach fields usually rely completely on gravity to move sewage along to long leach lines that allow the sewage to "leach" into the soil. Sometimes due to higher elevations a electrical pump is needed to get sewage to the leach field.

Common issues with leach fields occur when septic tanks are not pumped regularly and solids are allowed into the leach field. The solids clog the lines and don't allow sewage to leach out and be cleaned naturally. Depending on where the clog is, sewage can surface up into your yard or back into your home causing human and environmental health hazards. In order to make sure clogs don't occur in your leach field, you should pump the septic tank out regularly according to the chart above and switch the elbow in the diversion box at least every 6 months. Additionally, avoid parking cars, building anything or in anyway compacting the leach field. 

Subsurface Sand Filter




 Please see our Aerator Systems page.

EPA Grant Information

Union County Health Department was awarded a grant to fix and replace failing septic systems in Union County. If you know you have a problem with your system but do not have the funds to fix it, contact Holly Rast for information on how to apply!

Holly J. Rast
(937) 645-2043