Look for the following symptoms to determine if you have a problem with your septic system:

* Sewage backup in your drains or toilets. This is often a black liquid with a disagreeable odor.

* Slow flushing of your toilets. Many of the drains in your house will drain much more slowly than usual, despite the use of plungers or drain-cleaning products.

* Surface flow of waste water. Sometimes you will notice liquid seeping along the surface of the ground near your septic system. It may or may not have much of an odor associated with it.

* Lush green grass over the absorption field, even during dry weather. Often, this indicates that an excessive amount of liquid from your system is moving up through the soil, instead of downward, as it should. While some upward movement of liquid from the absorption field is good, too much could indicate major problems.

* The presence of nitrates or bacteria in your drinking water well. This indicates that liquid from the system may be flowing into the well. Water tests from your health department will indicate if you have this problem.

* Buildup of aquatic weeds or algae in lakes or ponds adjacent to your home. This may indicate that nutrient-rich septic-system waste is leaching into the surface water. This may lead to both inconvenience and possible health problems.

* Unpleasant odors around your house. Often, improperly vented or failing systems cause a buildup of disagreeable odors.