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septic system

How a Septic System Actually Works

You may never have heard of your septic system, but you can’t live without it. Your home’s personal underground wastewater treatment system, a septic tank, is buried somewhere in your yard. However, a lot of people forget about it until it needs repair or replacement.

A combination of technology and natural processes come together to treat wastewater that comes from the home, including kitchen, bathroom, and laundry drains. It's vital to remember that septic system maintenance is necessary even when a home is remodeled, or a new one gets built.

What Are the Parts of a Septic System?

Septic systems essentially have a pair of primary elements: the drain field and the tank.

  • Septic Tank: Your septic tank is much like a sewer, but for your home. It holds the wastewater for long enough for matter that floats to the top to separate from matter that sinks to the bottom, as well as from effluent—the leftover liquid in the middle.

As a container, the septic tank is water-tight and generally buried in yards. It's often made of concrete, fiberglass, or polyethylene and has a seal to keep its contents from escaping. Oils and grease float to the top, while solids sink to the bottom.

  • Drainfield: Also referred to as a soil absorption field, this is a covered excavation that's shallow. It's made alongside your tank in soil that's not saturated. This is where the liquid wastewater (the "effluent") gets dispersed into the soil.

Septic systems can also include pumps if you live in an area with sandy soil, or if you have a constructed wetland or organic matter like peat.

These systems disperse the effluent over constructed wetlands, sand, organic matter, and other substances, removing and neutralizing contaminants such as phosphorus, disease-causing pathogens, nitrogen, and more. Some even have designs meant for wastewater evaporation or wastewater disinfection before it gets released into the soil.

How Does It All Work?

The septic system typically follows this sequence:

  1. Wastewater leaves through the main drainage in your home.
  2. That wastewater travels to the septic tank buried in your yard.
  3. Wastewater is separated into three parts:
  • Solids sink to the bottom, forming sludge
  • Grease and oil float to the top, turning into scum
  • Effluent or the rest of the liquid stays in the middle
  1. Liquid wastewater ("effluent") gets leached from the tank into a drain field through perforated pipes.
  2. The liquid leaves through a T-shaped outlet and compartments in the tank; scum and sludge are held.
  3. Liquid wastewater goes through the soil thanks to the drain field.
  4. The soil naturally removes harmful viruses, coliform bacteria, and nutrients.
  5. Wastewater is trapped and dispersed as it goes through the soil.

It should be noted, however, that scum and sludge can be quite harmful when released into the soil. The best way to deal with it is to call on professionals for it to be pumped out of a tank.


The septic system plays a major role in plumbing situations, especially for homes. It consists of the septic tank and the drain field. Essentially, it works through compartmentalization as wastewater flows through it.

Trying to find septic tank services near Hayward? Contact A-1 Septic Tank Service, Inc. today! We’re a septic and non-hazardous pumping service provider in Contra Costa County and the surrounding areas.

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