What Is a Septic Tank and How Does It Work?

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What Is a Septic Tank and How Does It Work?

Septic tanks may be a foreign idea to many people. However, for homes that use one, they are critical and very familiar. A well-designed, correctly installed septic system can last a lifetime but failure to maintain a septic tank can cause it to fail in just a few years. If you've always lived in a home connected to the main sewage line, you're probably unfamiliar with septic tanks and what they are.

What is a Septic Tank?

A septic tank is a watertight container that collects wastewater from toilets, sinks, showers, and washing machines. They can have one or two compartments. New systems require two-compartment septic tanks, which do a better job of settling solids and are necessary for effective treatment. At the tank's intake and outflow pipes, there are tees or baffles. The inlet tee slows the incoming waste stream while decreasing sludge disruption. The outlet tee maintains the solids or scum in the tank.

Why are Septic Tanks Used?

Septic Tank History

The septic system is a relatively new waste-management technology. In 1860, when Jean-Louis Mouras combined the Ancient Greek notion of the flush toilet, which used clay pipes to carry wastewater outside his home, with the more "modern" concept of cesspools, which collected waste and were emptied manually from time to time, the first known septic system was invented.

However, Mouras also included an additional element he called the fousse Mouras (translated Mouras pit), a sealed tank that would contain wastewater and allow overflow to flow into the cesspool.

Modern Septic Tanks

Concrete or steel was used for early American septic systems, which were designed after Mouras's specifications. By the 1940s, septic systems had become widespread throughout the country. By the 1960s, when these systems began to fail, significant modifications were made to their design. Most current septic systems are built of more advanced materials, such as fiberglass, precast concrete, polyurethane, and other plastics.

Older septic systems were anaerobic in nature, but today's installations use an aerator to create a more efficient aerobic environment. One of the most significant changes in modern septic system usage is the recognition that regular, routine maintenance is necessary to keep it working properly.

How a Septic Tank Works

  • Water drains from your house via a single main drainage pipe into a septic tank, usually buried and watertight. The wastewater is kept in the septic tank long enough for solids to settle to the bottom and form sludge, while the oil and grease float to the top as scum.
  • The scum and sludge are kept from leaving the tank and traveling into the drain field by compartments and a T-shaped outlet. The liquid wastewater (effluent) is then discharged from the tank into the drain field.
  • The effluent of the septic tank is collected in the drain field. It consists of a network of perforated pipes sunk into gravel-filled trenches (2–3 feet wide) or beds (over 3 feet wide) in the soil. Wastewater trickles out of the pipes, through the gravel layer, and into the earth. The size and type of drain field are determined by an estimate for daily wastewater flow and soil conditions. If the drain field is filled to capacity with wastewater, it can overflow, sending sewage toward the ground surface or causing toilet and sink backups.
  • Every new drain field must be planned to include a replacement area specific to it. If your current system needs upgrading or repairs, the entire system may need to be replaced, including the drain field.
  • Finally, the wastewater percolates into the earth's soil, naturally eliminating harmful coliform bacteria, viruses, and nutrients. The term "coliform" refers to a type of bacteria commonly found in human intestines or other warm-blooded animals. It is an indication of human feces contamination.

Septic Tanks and Wells

Many people who use private wells for their drinking water rely on septic systems to treat wastewater. Water from toilets, sinks, showers, and other appliances is known as wastewater and can be harmful to human health. Wastewater includes germs, viruses, and nutrients that may make you ill if your water supply is polluted. Avoid flushing other chemicals or medicines down the drain or toilet, since they could contaminate your drinking water well.

Make sure your septic system properly treats the wastewater, and that your drinking water well is set back far enough from you and your neighbor's systems. Local building codes will list setback requirements specifying the distance a septic system must be from the well, as well as the size a septic system must be based on the number of occupants in the home.

Tank Depot is Your Best Resource for Septic Tanks

If you're in the market for a new septic tank or need to upgrade or repair your current system, check out the selection at Tank Depot. We carry a wide variety of septic tanks to suit any application, and our experts can help you choose the right one for your needs. Contact us today to get the price on a septic tank, or any of our water storage tanks and systems. We beat any price!

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