Fields & Septic Systems

Septic systems receive wastewater from private residences that are not connected to a public sewer system and treat that water before it is returned to the environment. Often referred to as a "drainfield" or a "leach field," a field is an important component of a typical septic system.

What is a Drainfield?

• A drainfield is an area of soil that has been set aside to receive and treat wastewater from a septic tank. According to the Department of Environmental Health in El Dorado County, California, a drainfield is composed of a series of perforated pipes laid over a bed of gravel and covered with either straw or untreated building paper. The drainfield is then covered with a minimal amount of topsoil, and grass is planted over it.

Function

• When a drainfield receives partially-treated wastewater from a septic tank, naturally-occurring, bacterial processes within the soil help to break down and remove organic waste and pollutants from the water. After being treated in a drainfield, the wastewater flows down deeper into the subsoil, where it is returned to the environment via groundwater. Some of the wastewater moves upward, where it is removed by evaporation or the capillary action of grasses.

Failure

• It is possible for a drainfield to fail. This usually occurs because the field and the surrounding soil is receiving more wastewater than it can handle. This can lead to flooding of the leach field, and can cause plumbing within the home to stop functioning correctly.

  According to the Environmental Protection Agency, some states require a homeowner to set aside a portion of property as a "reserve drainfield" in case the current drainfield fails.

Precautions

• According to the Environmental Protection Agency, there are several precautions that a homeowner can take to minimize disruptions to a leach field. Initially, a leach field should only be located in an area that contains a type of soil capable of processing a large volume of wastewater. Only grass should be planted over a leach field; larger plants can damage it. Vehicles should not be driven over a leach field, as this can pack down the soil and impede proper functioning. Homeowners should also ensure that excess water is not entering the leach field from unnecessary sources like rain gutters or sump pump drains.

Importance

• Because they ensure that wastewater is evenly spread through the soil and effectively treated, drainfields are very important to public health and the environment. The Environmental Protection Agency estimates that over 4 billion gallons of wastewater are produced by U.S. homes every day. Drainfields work to ensure that harmful pollutants and disease-causing microbes are effectively removed from this wastewater before it is returned to the groundwater supply. This helps to keep the water we use for bathing and drinking safe.