What to know when buying a house with a septic system

By Allstate

Last updated: January 1

It's a home feature that can make prospective buyers nervous: a septic tank.

Part of a home's wastewater system, a septic tank is found in households that aren't served by municipal sewers. Instead, these standalone systems are designed to dispose of and treat the household's wastewater independently, says the Environmental Protection Agency (EPA).

If you're considering buying a home with a septic system, here are some answers to frequently asked questions:

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How does a septic system work?

A pipe collects all the home's wastewater and transfers it to an underground, watertight septic tank. Here, solids (known as "sludge") settle to the bottom, and floatable materials (known as "scum") float to the top, says the EPA. Both are contained by the tank and are periodically pumped out by a professional.

The middle layer contains liquid wastewater (known as "effluent") that exits the tank into a buried drainfield in the yard, where the wastewater disperses into the soil, adds the EPA. The soil filters out contaminants and beneficial bacteria break down any organic materials.

diagram of a septic system

Photo By: wfeiden via Flickr, CC BY-SA 2.0.

Is the septic system related to the drinking water system?

No. Many homes with septic systems also have a private well. But, the septic system is entirely independent from the well. Its purpose is not to treat wastewater so it can become drinkable, but to safely disperse it in a way that prevents contamination.

What differentiates one septic system from another?

Typically, the size of the drainfield and the soil is what differentiates one septic system from another, says the University of Nebraska-Lincoln. The drainfield also has to be large enough to handle the liquid volume a family generates.

To avoid the possibility of clogging the system, don't use a home's toilet, sink or disposal as a wastebasket for dental floss, coffee grounds, kitty litter, paint or chemicals, advises the EPA. The EPA offers some additional do's and don'ts on its Septic Systems page.

How often should you get your septic tank emptied?

Pumping of the septic tank by a professional is required to remove the sludge and scum. The frequency is determined by the tank size and the level of home activity (how much wastewater is generated). Most septic tanks should be pumped every three to five years, says the EPA. But, some systems may need to be pumped more often — annually if needed.

What are the signs of a failing septic tank?

Besides pumping, the tank should be inspected regularly for leaks or clogs. Red flags that the system may have a clog include occasional bad odors and slowly draining or gurgling fixtures, the EPA explains.

What about maintenance costs?

Septic system maintenance costs depend on the tank and drainfield sizes, tank accessibility, and how far away waste must be hauled for disposal. Pumping a tank might cost between $250 to $500, says the EPA.

What should I do before buying a home with a septic system?

Know your state's rules. Some require a septic system inspection before a title transfer. But even if your state doesn't require an inspection, your lender might. (Conventional home inspections typically don't include an inspection of a septic system).

According to Zillow, an inspection can detail the system's condition, determine if it's sited a proper distance from a well (to avoid contamination), and can confirm the absence of invasive tree roots in the drainfield, which may damage the system.

Also, know the age of the system. Prices can vary widely if you do have to replace a system. The EPA says that a conventional system may cost between $3,000 and $7,000, but that an alternative system may cost even more.

Owning a home with a septic tank doesn't have to be scary. With the proper maintenance and care, you can enjoy your house for years to come.