How to Replace a Failed Septic Tank & Drain Field

Locate the failing septic tank and drain field. The area may be marked by raw sewage on the surface of the ground. Keep children and pets away from the contaminated area. Arrange to have the contents of the septic tank pumped into a truck and hauled away for disposal. The pump truck accesses the tank through a cover above the tank.

Excavate the ground around and above the septic tank. Find the problem with the tank. If the tank has collapsed, it needs to be replaced. If the tank is intact but pipes are broken, replace the pipes and leave the tank in place.

Locate the desired location for a new drain field. Check local zoning and building codes for allowed drain field placement. The fields commonly have to be at least 100 feet from wells or springs and 10 feet from property lines.

Excavate trenches for the drain field. The length of the trench varies depending on the number of bedrooms in the home and the soil absorption rate but is often as long as 300 feet and can be configured as a single trench or multiple parallel trenches. Each trench is about 18 inches wide and 3 feet deep. Dig trenches to connect the drain field to the outlet of the septic tank.

Place 6 inches of crushed rock in the bottom of the trenches of the drain field. Level the rock in the trench using a garden rake.

Place 4-inch PVC pipe in the bottom of the trench. Use solid pipe to connect the septic tank to the drain field. Use perforated pipe, sometimes called drain tile or pipe, within the drain field to allow the liquid to drain away. Connect the pipes together without glue to confirm the fit. Use PVC glue to connect the joints after confirming the fit.

Add another 1 foot of crushed rock over the perforated drainpipe. Level it in place.

Place roofing or building paper over top of the crushed rock. This prevents soil from washing into the crushed rock.

Backfill the trench with the soil removed during the excavation. Mound the soil above ground level to allow for settling.