A primer on old house septic systems and maintenance

By: Shannon Dauphin Lee , Contributing Writer
In: Old House Construction, Home Improvement Tips

Long before there was a public waste disposal system, there was the septic system. Today many old homes in rural and suburban areas still make good use of a septic tank that disposes of waste right there on the property. Understanding how the septic system works is essential in order to keep your property safe and your family healthy.

How a septic system works

When you flush the toilet, take a shower, run the washer or otherwise use water in your home, all that waste and water has to go somewhere. For many homes it goes into the municipal sewage system, where it then travels to a waste-water treatment plant. But for those who have a septic system, the discharged water and waste stays closer to home.

Whether you have a septic system or are on the municipal service, the pipes in your home are the same. If you have a septic system, the water and waste goes through those pipes to a septic tank. This tank is located on your property, buried underground. A quick search will usually turn up a cap that looks like a manhole cover with a handle, or some other sort of topper that you can remove with a little effort. That's the septic tank. It's watertight and extremely sturdy.

When waste-water is flushed out of your home, it goes into the tank. The water separates from the solids. The solids settle to the bottom of the tank, where they become a feast for anaerobic bacteria. Attached to the septic tank are outlet pipes that lead to a disposal bed or field. The liquid waste flows through the outlet pipes into the disposal bed, which are perforated pipes buried in deep trenches. These trenches radiate out from the septic tank. The liquid goes into the soil, where it is safely absorbed.

Fats and grease accumulate over time in the tank, creating a scum layer on top of the stored waste. Baffles inside the tank keep this layer from clogging up the disposal pipes. Though the anaerobic bacteria happily work away at the solid waste, the bacteria can't keep up with the amount of waste that flows from the typical home. That's where the maintenance comes in.

Care and maintenance of the septic system

The most important part of regular septic system maintenance is pumping out the tank. This can be done by professionals who come out to your property, pump out the tank and inspect it for any problems. In most places, pumping out the tank will cost between $200 and $300 every few years. During the pumping and inspection, the technician might test the outlet pipes to make sure they are working properly.

There are plenty of other things you can do to make sure your septic system stays in the best shape possible. Take care in what you flush down the toilet or pour into the sinks. Avoid disposing of anything that is hazardous or flammable, don't flush items that take a long time to break down (such as disposable diapers or feminine products), and avoid the biological additives that clever marketing insists you need. These additives can actually damage the anaerobic bacteria colonies in the septic tank, leading to faster sludge buildup.

Don't plant trees near the septic tank, as the roots could eventually work their way into the pipes or tank itself. Don't drive or park a vehicle over the disposal bed. Be careful of your water usage by installing low-flow toilets and showerheads, run only full loads of laundr,y and never connect your sump pump to the septic system.

Finally, report any issues to your septic contractor immediately. These include backup of sewage or water into the house, sewage seeping into the basement or lower levels of your home, problems with your drinking water, or lush grasses growing over your disposal field. These problems could indicate a small problem with the tank or a septic system reaching the end of its useful lifespan; only a contractor can tell you for sure.