A happy septic system is a good septic system Just don't forget where the field is


November 03, 1996|By Karol V. Menzie and Randy Johnson

SOMETIMES WE sort of slip into a column topic -- as Randy did while trying to negotiate a customer's driveway last week.

The steep, bumpy driveway can be a challenge on a sunny day, but this particular evening was dark and foggy. Randy's battered old 2-wheel-drive pickup just would not make it.

Shifting into first gear gave him just enough traction to keep from sliding into the woods, so he gave up -- parking in the grass and walking the rest of the way.

The customer had heard him thrashing around on the driveway and asked if Randy had seen the excavation.

"What excavation?"

"After 30 years, my septic field gave out and we're putting in a new one. The driveway is covered with mud."

Since it was too dark to see anything, Randy hadn't had a clue. But, he thought, septic system failure -- what a great topic for a column. How do septic systems work, and how can you prolong the life of your system?

(At this point, readers on public sewer lines may want to tune out and watch a Ross Perot infomercial instead.)

A typical home septic system consists of an underground, watertight container (the septic tank), a soil absorption drainage field (pipes buried in the ground, surrounded by gravel) and a box in between them that distributes liquid from the tank to the field.

Wastewater leaves the house through a pipe connected to the septic tank. Baffles in the tank slow incoming waste and prevent sewage from flowing directly through the tank into the drainage field.

The septic tank is where the real work goes on in getting household wastes ready for distribution into the drainage field. The tank has three levels: A bottom layer of sludge, which consists of heavy solids; a middle liquid layer, which consists of dissolved materials, such as detergents, and small amounts of suspended solids; and an upper layer of scum made up of solids that float, such as grease.

Solids and scum in the tank are digested by anaerobic bacteria (bacteria that live in the absence of oxygen). These little fellows liquefy up to 50 percent of the solids and scum. The liquid is carried out to the absorption field and the undigestible materials remain in the tank as sludge.

Every time raw sewage enters the tank, an equal amount of fluid is forced out. The fluid that leaves the tank can still contain small amounts of suspended and dissolved matter, including organisms that can cause disease. These liquids leach out through holes in the drainage field pipes, and bacteria in the ground continue the breakdown process.

Septic systems usually fail in one of two ways, according to Matt Watkins, sanitarian with the Harford County Health Department. One is when the drainage field becomes saturated from overuse or surface water, and the other when the tank contains too much solid material, which can get into the pipes and clog them.

"As far as good septic maintenance goes," Watkins said, "the most important thing is to pump the tank out on a regular basis."

Beyond that, there are plenty of things homeowners can do to make things easy for a septic system. The Cooperative Extension Service of the University of Maryland offers a pamphlet, "Septic Records and Maintenance Guidelines." (Check the extension service number in your county.) Some suggestions:


Don't overload the system. Don't run the dishwasher or washing machine in water-usage prime time, such as when toilets and bathtubs are in demand.

Don't use a garbage disposal and don't dump coffee grounds in the sink. Increased solids in the tank mean it must be pumped out more often.

Fats and oils will clog the system; never pour them down the drain.

Put paper towels, facial tissues, cigarette butts, disposable diapers and feminine hygiene products in the trash.

Natural bacteria work fine in breaking down sewage. Additives such as "starter enzymes" or yeast can disrupt the system by breaking up the sludge and scum layers too thoroughly and causing solids to flush out into the drainage field.

Don't use more than the recommended amount of detergent.


Direct downspouts and runoff away from the absorption field to avoid saturation.

Plants with shallow roots or dense ground covers are the best plants to put over the absorption field. Tree roots can clog or break pipes.

Don't allow the soil over the septic field to become compacted by driving or parking on it. Don't locate outbuildings such as garages and sheds over the field.

The tank should be pumped and cleaned regularly by a licensed professional. Make sure the baffles are inspected and the tank is checked for leaks. A 1,000-gallon tank serving a three-bedroom house with four residents should be pumped every one to three years.

And, though this may seem like an obvious point, it's a good idea to know where your system is.

We know someone who discovered when he began to have problems that the septic system was lost -- no one remembered where it was, and there were no clues such as inspection pipes. They spent weeks looking for it.

Randy Johnson is a Baltimore home-improvement contractor. Karol Menzie is a feature writer for The Sun.

If you have questions, tips or experiences to share about working on houses, e-mail us at homeworlark.net, or write to us c/o HOMEWORK, The Sun, 501 N. Calvert St., Baltimore 21278. Questions of general interest will be answered in the column; comments, tips and experiences will be reported in occasional columns.

Pub Date: 11/03/96

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