How does a septic system work? How to inspect and maintain a septic system?

Most of the waste that enters a septic system is decomposed by bacterial action in a 500- to 1,000 gallon septic tank. Undecomposed solid matter settles as sludge to the bottom of the tank; oily waste floats on top as scum. The liquid between, known as effluent, runs off through an outlet pipe into a drainage field and is absorbed into the ground.

To keep sludge or scum from clogging the drainage field, the water level must be maintained and the tank must be pumped out every 2 to 5 years, depending on its size and on the amount of waste it receives. Pumping is a job for a professional septic cleaning service.

Warning signs of an overloaded system include foul odors from your drains or over the drainage field, and lush vegetation over the tank. If water backs up into your drains, it may indicate that the drainage field is blocked by tree roots or clogged by sludge and scum. The roots can be cleared by a drain-cleaning service; a clogged field must be dug up.

To prevent problems, don’t put grease or slow-decomposing matter down drains or toilets. If there is no grease trap on the line between your kitchen drain and the septic tank, have a plumber install one. Avoid drain-cleaning chemicals; they kill the bacteria and enzymes that decompose the wastes. To hasten decomposition, mix 1/2 pound of brewer’s yeast in warm water and flush it down a toilet. Don’t use a commercial cleaning compound; it breaks up solids, which then flow into the drainage field, clogging lines that can’t be cleaned.