Common septic tank problems: A septic system is a self-contained water recycling system. Located underground in the yard, a water-tight tank receives and stores wastes from the house. Bacteria in the tank decomposes the wastes; sludge settles in the tank and effluent flows into the ground through a drain system. It eventually filters back down to groundwater sources.

If the waste is draining slowly or not at all, it might indicate a blockage in the main house drain or that the septic system itself is blocked up. (Don't use chemical drain cleaners in septic systems.)

A layer of sludge builds up in the bottom of most septic tanks as undecomposed solids gather there. Most septic tanks need to be pumped out every one to three years.

Dark-colored water on the surface of your drain field or a bad smell in or around the house may indicate more serious problems in your system, and since sewage is hazardous waste, it's not something you want to wait to deal with. Hire a professional to service your system.