Do All Houses Have Septic Tanks?

If not, what do they have?

Large farmhouse in the country
Photo: FrankvandenBergh / E+ / Getty Images
Large farmhouse in the country
Photo: FrankvandenBergh / E+ / Getty Images
Barbara Bellesi Zito
Contributing Writer
Updated October 5, 2023

Highlights

  • Most homes treat wastewater via a septic tank or the public sewer system.

  • A septic tank breaks down and purifies wastewater using beneficial bacteria.

  • If there is one on your property, it’s usually not hard to determine the location.

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All houses have either septic tanks or a connection to the public sewer for treating household wastewater. Homes located in more remote or rural places far away from public sewer systems typically rely on their own septic systems. Here’s what you need to know about this important household system.

What Is a Septic Tank?

A septic tank is an actual watertight tank that collects and treats wastewater. While there are some above-ground septic tanks, the majority are buried underground—a minimum of 5 feet from the house, to be exact, with the drain field located farther away. Tanks are made from concrete (the most expensive option), fiberglass, or polyethylene (plastic), all with different installation and maintenance requirements.

How Does a Septic Tank Work?

Whenever wastewater goes down the drain in your home—be it the sink, shower, tub, or toilet—its first stop is the septic tank. Here, the wastewater is broken down with the help of beneficial bacteria. Yes, you read that correctly. While bacteria are usually something to be gotten rid of elsewhere, they’re very good to have when it comes to your septic tank!

As wastewater flows into the tank, it separates into three parts:

  • Scum: This is the top layer of wastewater consisting of oil, fat, and grease—the runoff from washing all those dishes, as well as the soap that runs off from bathing. 

  • Effluent: Although this is the middle layer, it happens to be the cleanest. It results from what’s left in the water when the scum and sludge are pulled out from it.

  • Sludge: This is the bottom layer of wastewater, consisting of solid human waste and other heavier waste. It’s important for a professional to empty your septic tank every few years or so; otherwise, there can be a buildup of sludge.

These three levels are created by waste rising or sinking naturally. As such, it is not a quick process, though there are additives that can help the process along.

Wastewater comes in and goes out via two pipes connected to a septic tank. The inlet pipe receives the wastewater from your home, while the outlet pipe sends the wastewater into the drain field. The drain field is where the wastewater is purified and eventually sent back into the soil.

How Do You Know If a House Has a Septic Tank?

Home septic tank and vent in the yard
Photo: Kinek00 / iStock / Getty Images Plus / Getty Images

We could simply file this answer in the “if you know, you know” category because odds are slim that you purchased a house without someone informing you of how its wastewater is treated. But we can do a little better than that. Let’s pretend for a moment that everyone has been distracted by all the other things that happen during the homebuying process and that the sewage treatment system has been left out of the conversation accidentally. 

Do all houses have septic tanks in your new neighborhood, or are some hooked up to the public sewer? Here are some questions you can ask yourself to determine the answer:

How Old Is Your Home? 

When it comes to homes, the older they are, the more likely it is that they’re connected to a septic tank. This is particularly true if you live in a rural area, but homes in suburban areas could still be hooked up to a septic tank even if there’s a public sewer system in place.

What Type of Home Is It? 

If you live in an apartment, condo, or co-op, it’s more than likely that you’re connected to a city sewer system. In general, multi-family homes are in denser urban areas and hooked up to the public sewer. Though there are some very large septic tanks, they’re not big enough to handle that many families; they are typically reserved only for single-family homes and townhomes, like duplexes and triplexes. 

What Do the Property Records Say? 

Your property records are a wealth of information regarding your home and neighborhood’s history. Yours are on file with the central office in your town or municipality and will clearly indicate how wastewater is treated on your property. In fact, the records will likely point you directly to where the septic tank or sewer line is connected to your property. 

What Does Your Real Estate Agent Say? 

These days, most real estate listings online indicate whether a home operates on a septic tank or a sewer system. To confirm, you can always ask the real estate agent who worked with you to purchase the property, as they’ll have this info and other interesting information about your property. 

Can You Find the Lid? 

Your septic tank is beneath the ground, but there’s one way to access it—the lid. It’s made from concrete or plastic and flush with the ground, but you can usually find it just by walking the perimeter of your yard at least 5 to 10 feet from your home. Assuming it’s got a metal handle, as many of them do, you can even head out on a backyard hunt with a magnet in tow to find it.

Is There New Grass Growth?

You might not have grass in your backyard, depending on your landscape design. But if you do and you see a patch of grass that’s a brighter green than the rest, you might have found the drain field of your septic tank. But don’t admire your lush lawn for too long. You’ll want to call a septic professional to have it checked because new grass growth could be a sign that there’s a leak or other problem with the drain field. 

How Much Does It Cost to Install a New Septic Tank?

It will cost an average of $6,500 to install just a new septic tank, with a common range between $5,000 and $8,000, depending on the size, type of material, and complexity of installation. Installing a new septic system in its entirety, on the other hand, is much pricier, ranging between $10,000 and $25,000. This is why you’ll need to be on a proper maintenance schedule with your local septic tank company to avoid any issues that could escalate into needing to replace the entire tank and drainfield.

Finding out if your house has a septic tank isn’t hard, but it’s something you should do as soon as possible. If you think a backed-up toilet is bad news, there’s more in store for you with a faulty septic system that you didn’t know existed until now!

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Learn more about our contributor
Barbara Bellesi Zito
Contributing Writer
Barbara Bellesi Zito is a freelance writer from Staten Island, NY, covering real estate investing and home improvement for Millionacres, Apartment Therapy, and others.
Barbara Bellesi Zito is a freelance writer from Staten Island, NY, covering real estate investing and home improvement for Millionacres, Apartment Therapy, and others.
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