What Is a Septic Drain Field?

Did you know that without a properly functioning septic drain field, your septic tank may overflow, leaving the area around it (a.k.a., your backyard) a smelly, wet mess? Septic drain fields consist of a series of underground pipes that safely filter your septic tank's wastewater into natural ground soil. Septic systems have several working parts, and all parts must work together to ensure optimal safety and hygienic operation.

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What Is a Septic Drain Field?

When wastewater from a home plumbing system enters a septic tank, it goes through a filtration process that separates solid waste from the liquid. The liquid waste is called "effluent."

A septic drain field (also called a leach field) is a covered trench that holds a series of downward-sloping pipes that are connected to the septic tank. Once the solid waste is separated from the wastewater in the septic tank, the effluent exits the tank and enters the drain field through the underground pipes. The pipes filter the water and release it into the underlying soil. From there, the soil naturally eliminates bacteria and other impurities through a process called percolation. After the percolation process completes, the treated water is naturally discharged into groundwater.

What's the Purpose of a Septic Drainage Field?

Drain Fields Help Your Septic Tank System Filter Out the Bad Stuff

A drain field works by breaking down and eliminating wastewater and other impurities that enter the field through a home's septic tank. Homes that utilize septic systems rely on drain fields to eliminate harmful bacteria and pathogens from their wastewater before it returns to the natural water cycle.

Leach Fields Prevent Wastewater Buildup

Drain fields are also specifically designed to filter wastewater into underlying soil while preventing its ingestion by animals in the area. Without drain fields, wastewater would build up inside septic tanks, causing foul odors, sewage backups and flooding, all while increasing the risk of illness.

How Does a Septic Drain Field Work?

Parts of a Drain Field

The two main components of a septic system are the septic tank and the septic drain field. For homes that have septic systems, all water that comes from the home's plumbing system travels into a single main drainage pipe. When the water enters the drainage pipe, it flows into the septic tank, where solid waste separates from the liquid and settles at the tank bottom.

The separated liquid wastewater then flushes through the tank and into the leach field. From there, a series of underground pipes, surrounded by a layer of gravel that helps catch solid material, filter the water into the underlying soil. The soil particles then naturally treat the water to eliminate potentially harmful pathogens.

Leach Field Pipe Materials

Drain field pipes typically consist of PVC or hard resin material. According to The Spruce, PVC is most common. In either case, the pipes are perforated to let the liquid effluent through.

What Is the Life Expectancy of a Septic Drain Field?

When properly maintained, a drain field should last between 20 and 30 years. Some factors that may affect a drain field's longevity include soil conditions and the overall volume of wastewater it filters on a regular basis. Scheduling regular leach field maintenance is also an important factor when calculating its lifespan.

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How Deep Is My Septic Drain Field Buried?

While specific regulations can vary based on the area you live in, most states require that septic drain fields must be at least 10 to 20 feet away from a home's structure. The leach field should be located within at least 10 feet or so of the tank. However, it's important to note that not all septic systems are installed in the same fashion, so it may be difficult to pinpoint its exact location.

Locating Your Leach Field

To make the process of finding your drain field easier, consider scheduling an inspection with a professional plumber or septic system installation specialist. They should be able to survey the area and easily find your drain field by gauging the location of your septic tank and assessing the soil and grass.