Septic System Design and Usage

In order to keep your septic system healthy and lasting long it’s good to know a thing or two about how it works, both its design and how to use it. Here’s a brief overview of septic system design and usage.

Septic System Design

A septic system is designed to be hassle-free and self-regulating with only occasional intervention from the homeowner. If you have the septic system inspected annually and pumped when necessary you really shouldn’t have many problems.

Basic septic system types have two major components: the septic system tank and the leach field (also called a drain field or absorption field). There are variations in the design and construction of septic systems, but the concept is the same.

The Septic System Tank

Tanks can be made of concrete, fiberglass or plastic. Most tanks have two chambers, each with an access lid. The first or primary chamber is larger and retains the majority of sludge and scum. The smaller secondary chamber allows the effluent to further settle and break down before entering the leach field. Tanks may vary in size from 1,000 to 2,000 gallons for most residential systems. Generally speaking, the size of your tank is based on the number of bedrooms in your home or as specified by local building and health department codes. Example: 2 to 3 bedroom home will have a 1,000 to 1,250 gallon tank.

The Leach Field

The leach field is an underground network of perforated pipes, which is connected to the secondary chamber via a pipe with Tee fittings, lying in a gravel lined trench. The pipes distribute the effluent over a large earth covered gravel bed (usually several hundred square feet).

The soil under the leach field is another important part of the treatment process. The effluent slowly percolates through the gravel layer and enters the soil. Natural bacteria in the soil further digest the effluent before it enters the groundwater. Too much water (excessive household water, rainwater, broken sprinkler system leaking into the tank through a cracked lid) could force sludge and scum to the leach field. Driving a vehicle over a leach field will compact the pipes, gravel and soil, closing the pores. The water cannot seep down and is forced to the surface. If gravel and soil layers become plugged or oversaturated, the field may have to be replaced.