A septic system should effectively accept liquid wastes from your house and prevent biological and nutrient contaminants from getting into groundwater, wells, or nearby lakes and streams. When this does not work correctly, the system is failing.

For example, when waste backs up into your home or liquid is bubbling up in your backyard, the system has failed. If significant amounts of biological or nutrient contaminants reach your well or surface waters, the system has also failed, even though it may appear to be working.

Most septic systems will fail sometime. They are designed to have a lifetime of 20 to 30 years, under the best conditions. Eventually, the soil around the absorption field becomes clogged with organic material, making the system unusable.

Many other factors can cause the system to fail well before the end of its 'natural' lifetime. Pipes blocked by roots, soils saturated by storm water, crushed tile, improper location, poor design or installation can all lead to major problems.

But by far the most common reason for early failure is improper maintenance. When a system is poorly maintained and not pumped out on a regular basis, sludge (solid material) builds up inside the septic tank and then flows into the absorption field, clogging it beyond repair.

Article courtesy MSU Extension