Water Resources Center

The Water Resources Center is affiliated with the College of Food, Agricultural and Natural Resource Sciences and University of Minnesota Extension.

Preventing Costly Drainfield Repair

Printer-friendly version (.pdf)

A septic system's effectiveness is greatly influenced by how it's used and maintained. Treatment of disease-causing pathogens and nutrients is done in the soil part of the system.

This soil treatment system can be a drainfield, mound, or drip dispersal unit. Overloading it with water and solids can clog the soil. Large amounts of water flowing through your system are damaging; solids might be flushed out before the tank separates them from the water. An example is the washing of many loads of laundry on the same day. Spacing heavy water-using jobs, such as laundry, throughout the day and week helps prevent overloading. Water from roof drains or snow melt flowing onto or collecting in drainfield areas should be avoided.

Lack of proper septic tank cleaning can cause biological overloading. By adding "dirty" water to the soil treatment system, a thickened layer called the biomat becomes thicker than desired. The soil's ability to accept water slows. Effective treatment is decreased.

Driving heavy vehicles on the drainfield or mound system during or after construction can damage it. Soil treatment depends on natural, uncompacted soil to treat wastes. This is especially important in winter, when a vehicle's weight can drive the frost deep into the soil. This prevents effective treatment from occurring. Nothing heavier than a riding lawnmower should be driven over any part of the septic system. In addition, people should stay off the area in wintertime to prevent freezing.

Good vegetative cover, usually grass, is planted over soil treatment systems. Mow it regularly. Mowing is necessary to encourage growth without using fertilizer. The vegetative cover helps remove nutrients such as nitrogen and phosphorous. Do not plant trees or other plants with deep roots within five feet of the soil treatment system. Be sure to keep gophers and other rodents out of the soil treatment area.

By following these management practices and others found in the Septic System's Owner's Guide, Extension Publication PC-06583, you will prevent costly repairs & protect your family's health & environment. For more information, contact your local Extension office.