How Does a Septic System Work? 5 Things to Know


The phrase “septic tank” on a property listing is notorious for deterring potential buyers – they may see the system as outdated, expensive to repair, or difficult to maintain. Septic tanks don’t have to be scary, however – with a solid maintenance record and inspection, a septic tank and its parts can easily last for decades. If you are considering a new home with this system buried, you are not automatically deciding because you do not know the answer to the question “How does a sewer system work?” Read this first.

1. A sewage treatment plant is supposed to filter wastewater.

The first step in removing any discomfort about a sewer system is to understand its purpose and how it works. Let’s start with the different parts. The system consists of a large septic tank, a drainage field (also known as a “leach field”), a network of perforated pipes that spread out from the septic tank and discharge the filtered wastewater into the ground, a distribution box and baffles that are buried underground .

How does a sewage system work? The wastewater from your home – from toilets, sinks, showers, and appliances – exits the house through the pipes and into the tank. In the tank, the solid matter (also known as “sludge”) settles on the bottom. Build-up over time provides a luxurious home for beneficial anaerobic bacteria, which break down the solids and release fat, oil, and fats (the “scum”). These byproducts rise to the top where they hang in the tank and are kept separated by a series of baffles. Meanwhile, the remaining sewage (also known as “sewage”) flows through outlet pipes into the disposal bed or drainage field, where it is slowly and safely filtered from the floor.

How does a septic system work?  This diagram explains


2. These systems require attention and maintenance to keep them running smoothly.

Maintaining a sewer system is pretty straightforward. Here’s how:

  • Pay attention to what you are sending through the system. Paint, chemicals, cat litter, coffee grounds, disposable wipes, diapers, and feminine products should never go down the drain as they could clog the sewer system.
  • Avoid using additives in the system. According to the National Small Flows Clearinghouse, there are two types of additives: chemical and biological. Although these products are marketed to accelerate the breakdown of solids and improve the condition of the drainage field, they usually do damage to the bacteria that are designed to keep the system functioning.
  • Never park or drive across the drainage field as the weight of the vehicle could damage the pipes.
  • Use caution when planting bushes or trees near the drainage field. Some water-loving species, like weeping willows, can send roots down the drain field, outlet pipes, or even the septic tank itself. The Virginia Cooperative Extension suggests a good rule of thumb: if a tree gets 25 feet tall, keep it at least 25 feet from the drainage field.
  • On average, have the tank pumped out by a professional septic tank service every two or three years. As a rule, the specialist carries out a visual inspection of the component at the same time.
  • Contact a specialist at the first sign of a possible failure (see below)! The sooner you call, the cheaper a solution can be.

3. It is important to recognize the signs of failure.

The failure of a sewage system can initially go unnoticed. Slow internal drains and gurgling noises from these external drains are often the first sign. Then there may be occasional bad smells coming from the septic tank, drain field, or drains around the house. Sewage flowing back into the house; or difficulty flushing toilets. Outside, the vegetation above the drainage field can suddenly become lush and crowded, indicating a possible clogging or rupture of the outlet pipes.

How does a septic system work?  5 things home buyers should know


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4. Don’t fall victim to common misunderstandings.

Lots of misconceptions (even myths) about septic tanks can give someone a break from thinking about a house that has one. Let’s get the record straight:

  • Nobody really has a septic tank anymore. In fact, the Environmental Protection Agency (EPA) says about 20 percent of households have a sewer system – that’s one in five.
  • Septic tanks routinely fail. If properly maintained, a sewer system can last up to 40 years or even longer, according to the EPA.
  • Septic tanks stink. A properly maintained sewer system should not give off unpleasant odors. If you smell a bad smell coming from the drains or the septic area itself, there is a problem.
  • A sewer system can contaminate a well. If a system is properly installed and regularly maintained, it will not contaminate a well on the property. According to the Centers for Disease Control (CDC), the system must be located at least 50 feet from the well to ensure the separation of drinking water and wastewater.
  • The sewage system is examined during a house inspection. A home inspection typically focuses on systems within the home. Hence, it seldom includes more than a cursory glance at the septic tank. For a complete picture, find a professional who knows exactly how a sewer system works and how to thoroughly inspect it.

5. Know how to find the best septic tank inspector.

When you bid on a home, that listing almost always depends on the results of a full inspection of the property – including the sewage treatment plant. It’s important to remember that what’s on a seller’s disclosure form is not a good substitute for an inspection. The homeowner usually does not have the skills or equipment to properly inspect the system. If there are problems, the homeowners may not be aware of them.

It’s also important to note that a home inspection usually doesn’t involve a good look at the sewer system. A general home inspection assesses the house itself, the systems in the house (e.g. plumbing and electrical wiring), the condition of the roof, and possibly some of the outside areas. A thorough look at the sewer system often requires training that a general house inspector may not have. Therefore, always contact a septic tank professional to perform the inspection.

As with hiring most home maintenance professionals, it is best to see an inspector with an excellent reputation. Your neighbors and your realtor may have some good pointers to offer. Note that selecting an on-site person also ensures that they are familiar with the applicable regulations. Different septic tank rules may apply in neighboring communities. Call each potential inspector and ask questions about how they do the job. For example, some use cameras to view the junction box and drain field while others dig to conduct their inspection. This can make a difference in cost, but it can also make a difference in aesthetics, especially if you don’t want the delicate landscaping to be disturbed.

Once the inspection begins, the professional looks for pumping and maintenance records, looks for signs of leakage or backup, measures sludge and foam levels, determines the age of the tank, and much more. The inspector also assesses the condition of the drain field, tank, and all related parts and confirms that the tank is the correct size for the house. If the house has additions made after the initial installation of the septic tank, an inspector can make recommendations on housing. For example, a 2 bedroom house will need a tank that is a different size than a 3 bedroom house.

Professionals know septic tanks

Get in touch with trusted specialists in your area and receive free, non-binding offers for your project.

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