Conventional Septic Systems

Conventional septic systems are the most common. Most people know them as a Leach Field System or an Overflow System. A conventional septic system has two main components: a septic tank and a drain field. These systems are gravity fed.

A properly designed septic system is free from odors should last for decades (up to 50 years) with minimal maintenance.

Septic Tank

The septic tank serves to separate solids from wastewater. A septic tank typically has one or more plastic or concrete tanks. The tanks are normally between 1000 to 2000 gallons. Liquid enters initially through a wastewater pipe. One of the most common tank configuration is a two-chamber tank, each with a manhole cover for easy cleaning and service.

When wastewater enters, it goes into the first chamber or tank, which allows solids to settle. Solids will be anaerobically digested, which reduces the volume of the solids. Scum floats to the top and the liquids flow through to the second chamber or tank. In this tank, further settlement occurs. Excess liquid is now in a more clear condition, so it is passed through an outlet to the septic drain field (the leach field).

Drain Field

Once the excess liquids are sent to the drain field, the remaining impurities are trapped and eliminated into the soil. The excess water is eliminated via percolation into the soil, along with evaporation. It is also absorbed and used by plants via their root system. All of this happens before any contaminants reach groundwater or surface water.

The Leach Field is made up of a network of pipes. The pipes are lain in a trench and then covered by stone. Numerous holes are present in the system, which distributes the wastewater throughout the field. The size of the field depends on multiple factors, including the volume of wastewater anticipated and the absorption level of the soil.

The septic system operates typically by gravity alone. However, if the land or topography does not allow gravity to do its thing, a lift pump may be used. Other designs may include siphons or other devices that increase the volume and speed of outflow to the drainage field. North Texas Water Works will design the best system for superior performance and longevity.


Health departments often require a percolation test (“perc” test). This establishes the suitability of drain field soil. A licensed designer or engineer may be required. They will work with the city or agency to determine the best design. Why does the soil matter?

Wastewater contains sewage from toilets. This sewage can contain viruses and bacteria which could cause disease. Unlike a municipal sewage system, a septic system can’t use the same methods to disinfect the waste. So the soil acts as the disinfectant that kills the viruses and bacteria. A drain field that is functioning correctly will hold and deactivate the pathogens before they can leave the drain field.

The soil should be permeable enough for the waste to percolate away from the drain field. However, the soil must also be fine grained enough to filter out and of the pathogens before they can reach water wells or surface water supplies. This is the goal of the percolation testing.

A percolation test is required prior to installation to ensure the porosity of the soil is adequate to serve as a drain field.

Is a Conventional Septic System right for me?

We can help you figure that out. Our experienced, highly trained professionals can help you select the proper septic system for your property. North Texas Water Works will inspect your property and give you a detailed quote. We can also answer any questions you may have. Placement of the septic system is very important.

Call North Texas Water Works today for a FREE Septic System Quote.

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