How Your Septic System Works
Septic tanks are water-tight receptacles made of either concrete or plastic, designed to recieve wastewater from your home. The tank separates the solid waste from liquid waste (the solids settle at the bottom of the tank and the greases and fats rise to the top). The relatively clear liquid waste gets pushed through the septic tank into the drainfield, where it is cleaned and released back into the ground.
What Can Go Wrong
There are several things that can contribute to a septic system malfunction, including improper operation and maintenance, improper installation, or unsuitable soil or environmental conditions. There are several undesirable effects of a malfunction that you may recognize, such as sewage backing up into your home or unusual lush growth of vegetation in your yard. Malfunctions are always bad and can be very harmful to the environment, contaminating groundwater or local streams and lakes.
(This is why it is smart to get your system tested when you are selling your home - no potential buyer wants to deal with these issues.)
Hazards to Septic Systems and What You Can Do to Maintain Yours
Septic systems are alive with biological matter that helps decompose and treat the sewage but the bio balance can be disrupted by oils and grease going down your drain, harsh drain cleaners, paints and paint thinners, feminine products, papertowels, and cooking materials like bones, eggshells and coffee grounds. None of these things should go into your septic system.
Some people pour septic tank additives or cleaners into their system in the attempt to keep it in running order, but these products are not necessary to the health of your system and can do more harm than good to your plumbing and the bio balance in your system.
The single best way to preserve your septic system is to have it pumped once a year for a large system and every other year for a small system.