How A Septic System Works

Before we dive into the inner workings of your home’s septic system, it is first necessary to understand what a septic tank is. In short, about 25% of all homes in America use a septic system, and in small communities, this number is as high as 61% of homeowners.

The septic tank is a central repository for wastewater that comes from your home’s sinks, showers, toilets, dishwasher, and other appliances are hooked up to your home’s plumbing system. Anything that goes through your home’s piping (from toilet paper to egg shells) eventually winds up underground in this big steel or concrete vault. There are county-specific ordinances that govern the septic tank’s distance from your home, depth below ground level, and proximity to public water sources.

Now, to walk you through how a septic system works, we are going to explain what happens from the moment you turn on the sink and use exactly 1 gallon of water:

Flowing Out of the Home: You turn on the sink and water whooshes down the drain. Now that this water is no longer in use, we call it sewage (or sometimes, more pleasantly, wastewater). Gravity is the main driving force for pulling the sewage through your home’s piping into one main exit pipe. All water from showers, toilets, and sinks eventually collects in the home’s main exit pipe.

Entering the Septic Tank: Water flows through the home’s exit pipe and enters the septic tank through an inlet baffle. Whatever amount of water enters the septic tank, an equal amount is dispelled through the opposite end. The balancing effects of gravity keep an equal amount of water in the tank at all times. In our case, as 1 gallon of water enters the tank, another gallon is expelled from the opposite side.

Inside the Septic Tank: The septic tank is divided into two main compartments:

  • In the first septic compartment, we find the main buildup of solid material. The stuff that sinks to the bottom is called sludge, while the material that floats on top is called scum. In between the two layers of waste is liquid effluent, accounting for roughly 2/3 of the first compartment’s contents. Liquid effluent is mostly just water, free of floating or solid debris.
    • A small opening or pipe is driven just deep enough to avoid collecting top-layer scum, and just short enough to avoid collecting lower-level sludge. This means that liquid effluent is really the only thing entering this pipe, which flows directly into the second compartment.
  • The second compartment purely acts as a second line of defense, trapping any excess sludge or scum before it leave the septic tank. In 1992, federal regulations mandated the introduction of the tank’s second compartment. While they are not entirely necessary, they make wastewater treatment more safe and efficient.

Leaving the Septic Tank: Because our current example uses 1 gallon of water entering the tank, a different gallon of water now flows out of the tank’s second compartment through the outlet baffle. The water that leaves the septic tank isn’t exactly safe to drink, but it is processed enough to be free of floating and solid waste. It now enters the drain field.

The Drain Field: The final step of your home’s septic system is the drain field, which is made up of elongated pipes (usually 3)  that are as long as 100 ft. These plastic, perforated pipes are also buried several feet beneath the ground, but carefully surrounded by a thick layer of gravel and sand. Water equally disperses through the 3 distribution pipes and slowly leaks into the ground. The mixture of sand and gravel creates a process called filtration that physically processes the water as it moves slowly downward. Gravity again does most of the work, pulling the water in the earth’s natural bedrock, until the water is naturally absorbed into groundwater.

As you can see, the septic system is actually very interesting! There are no moving parts that filter your home’s wastewater, just a series of carefully placed pipes that rely on natural processes to restore the water to its original properties. Every shower you take and toilet you flush is eventually filtered by your home’s septic system until it becomes part of the groundwater deep beneath your home!

Now that you know a little bit more about your septic system, you can better understand how Reliable Rooter diagnoses and fixes problems in your septic tank.