The 5 Biggest Questions Home Buyers Have About Septic Systems

You’ve found the perfect home and it has a septic system. Here’s what you need to know about how it works and how to keep it running smoothly.

By Theresa Clement and Shannon Lee and Bob Vila | Updated Oct 26, 2021 7:34 PM

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septic system septic tank diagram


The phrase “septic system” in a home listing is notorious for scaring away potential buyers. Some home buyers may see the system as antiquated, expensive to repair, or hard to maintain. But septic systems don’t have to be scary.

With a solid maintenance record and a good inspection, a septic tank and the associated parts can easily last for decades. If you’re considering scheduling a viewing to see an appealing home that has this type of system buried out back, don’t automatically opt out without learning the facts about septic systems.

Keep reading to find out how septic systems work, the misconceptions about septic systems, how to maintain them, how to find a septic system inspector, and the signs that one may be failing.

1. How do septic systems work? 

A septic system is designed to filter wastewater. It consists of a large septic tank, distribution box, baffles, and drainfield that are buried underground. The drainfield is also called a septic field or leach field, and it’s the network of perforated pipes that spread out from the septic tank and release the filtered wastewater into the soil.

The wastewater from your home—from toilets, sinks, showers, and appliances—exits the house through the pipes into the tank. Once in the tank, the solid matter (also known as sludge) settles to the bottom. The buildup over time provides a luxurious home for beneficial anaerobic bacteria, which work to break down the solids and release the grease, oil, and fats (the scum).

The byproducts rise to the top, where they hang out in the tank, kept separate by a set of baffles. Meanwhile, the remaining wastewater (also called effluent) flows through outlet pipes into the disposal bed or drainfield, where it is slowly and safely filtered by the soil.

septic system septic tank diagram


2. What are common misconceptions about septic systems?

There are many misunderstandings (even myths) about septic systems that can give someone pause when considering buying a home that has one. Let’s set the record straight on some of the most common misperceptions.

  • Nobody really has a septic system anymore. Actually, the Environmental Protection Agency (EPA) says about 20 percent of homes have a septic system—that’s one in five residences.
  • Septic systems routinely fail. With solid maintenance, a septic system can last for up to 40 years—or even longer, according to the EPA.
  • Septic systems stink. A properly maintained septic system would not emit any unpleasant odors. If you smell a bad odor emitting from drains or the septic area itself, there’s a problem.
  • A septic system can contaminate a well. If a system is installed properly and maintained regularly, 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 a well to help ensure the separation of drinking water and wastewater.
  • A home inspection will look at the septic system. A home inspection tends to focus on systems within the home; therefore, it rarely includes more than a cursory look at the septic. To get a complete picture, look for a professional who knows exactly how a septic system works and how to thoroughly inspect it.

3. How do you maintain a septic system?

Septic systems require attention and maintenance to keep running smoothly. The good news is that maintaining a septic system is rather simple. Here’s how to keep it working properly.

  • Be careful of what you send through the system. Paint, chemicals, kitty litter, coffee grounds, disposable wipes, diapers, and feminine products should never be sent down the drain. Any of these could clog the septic system.
  • Avoid using any additives in the system. According to the National Small Flows Clearinghouse, there are two types of additives: chemical and biological. Though these products are marketed to do everything from accelerate the breakdown of solids to improve the state of the drainfield, they usually wreak havoc on the bacteria that are supposed to keep the system working well.
  • Never park or drive over the drainfield, as the weight of the vehicle could damage the pipes.
  • Be careful when planting bushes or trees near the drainfield. Some water-loving species, such as weeping willows, can send roots into the drainfield, outlet pipes, or even the septic tank itself. The Virginia Cooperative Extension suggests a good rule of thumb: if a tree will grow to be 25 feet tall, keep it at least 25 feet away from the drainfield.
  • Get the tank pumped out every two or three years, on average, by a professional septic service. Typically, the professional will also conduct a visual inspection of the component at the same time.
  • At the first sign of potential failure (described below) call in a professional! The sooner you call, the cheaper a fix might be.
septic system septic tank diagram


4. How do you find the best septic system inspector?

When placing an offer on a home, that offer is almost always contingent on the results of a full inspection of the property—including the septic system. It’s important to remember that what is said on a seller’s disclosure form is not a good substitute for an inspection. The homeowner typically won’t have the skills or equipment to properly inspect the system. If there are hidden problems, the homeowner might not be aware of them.

It’s also vital to note that a home inspection usually doesn’t include a good look at the septic system. A general home inspection will evaluate the home itself, the systems within the home (such as plumbing and electrical), the condition of the roof, and possibly some of the exterior areas. A thorough look at the septic system often requires training that a general home inspector might not have. Therefore, always go to a septic system professional to get the inspection.

As with hiring most professionals for home maintenance, it’s best to seek out an inspector with an excellent reputation. Your neighbors and your realtor may be able to offer a few good leads. Keep in mind that choosing someone local will also ensure that they’re familiar with applicable regulations—neighboring municipalities may have different rules regarding septic tanks. Call each potential inspector and ask questions about how they handle the job; for instance, some might use cameras to look at the distribution box and drainfield, while others might dig to do their inspection. This can make a difference in cost, but it might also make a difference in aesthetics, especially if you don’t want delicate landscaping disturbed.

Once the inspection begins, the professional will search out pumping and maintenance records, look for signs of leakage or backup, measure the sludge and scum levels, establish the age of the tank, and more. The inspector will also assess the condition of the drainfield, tank, and all associated parts and confirm that the tank is properly sized for the home. If the home has additions that were created after the septic tank was initially installed, an inspector may make recommendations to accommodate. For instance, a two-bedroom home needs a different size tank than a three-bedroom does.

septic system septic tank diagram


5. What are the signs that a septic system needs to be replaced? 

It’s important to recognize the signs of a coming failure before it happens. Failure of a septic system might go unnoticed at first. It’s helpful to watch for the signs, so you can schedule a replacement before it fails.

  • Gurgling sounds from exterior drains.
  • Slow-moving interior drains in bathtubs and sinks.
  • Bad odors are emitted from the septic tank, drainfield, or drains in the home.
  • Wet areas appear above the drainfield.
  • Sewage is backing up into the house.
  • It’s taking longer for toilets to flush.
  • Outside, the vegetation over the drainfield might suddenly become lush and full, indicating a possible blockage or break in the outlet pipes.
septic system septic tank diagram


Final Thoughts

Used in about 20 percent of homes in the United States, septic systems remove wastewater from a home. While septic systems may require a little more work than using a public sewer system, they aren’t as difficult to keep running as their reputation may suggest.

With regular inspections and an eye peeled for the signs of possible issues, a well-maintained septic system can last 40 years. For homebuyers considering a property with a septic system, it’s important to have the system looked over by a professional inspector.

septic system septic tank diagram

Source: WikimediaCommons

FAQs About Septic Tanks and Septic Systems

There’s a lot to learn about septic systems. After taking in the above information, you may still have questions about how septic systems work and how to maintain them. Here are answers to some common questions about septic systems.

Q: How does a septic tank work? 

After wastewater enters a septic tank, the solid matter settles to the bottom and creates a bed of beneficial anaerobic bacteria that work to break down the solids and release the fats.The byproducts rise in the tank and are kept separate by a set of baffles.

Q: What are the three types of septic systems?

The three types of septic systems are conventional system, chamber system, and drip distribution system. Conventional systems are typically used for houses. Because it is made of a series of closed chambers, a chamber system is usually chosen for high water table areas. Drip systems tend to be easier to install, but require more maintenance.

Q: How many years does a septic system last on average?

According to the EPA, a septic system can last 40 years if it is well maintained. Be sure to have a septic system inspected before you buy the home, so you have an idea of how many years that septic system is expected to last.

Q: What is the alternative to a septic tank?

The alternatives to a septic tank include an aerobic treatment system, composting waste, and a drip system.

Q: What chemicals are bad for a septic tank?

Chemicals like oil-based paint, paint thinners, lubricants, gasoline, weed killers, foaming cleaners, and chlorine-based cleaners are bad for a septic tank. They can contaminate the surrounding environment, and kill the bacteria that’s needed inside the septic tank, making it difficult or impossible for matter to break down.

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