How Much Does a Mound Septic System Cost?

If your home requires a mound septic system, be prepared to pay significantly more than if you were installing or replacing a conventional septic system. While the cost of any septic system correlates to the size of the home or building it must service, figure that a mound septic system will set you back a minimum of $10,000 for a smaller dwelling or building and $20,000 or more for larger construction. Depending on your area of the country, the costs may prove to be considerably higher. Keep in mind that a mound septic system is not usually the first choice for any contractor or homebuyer. A mound septic system is generally installed because the land cannot support a conventional septic system.

In areas with high water tables, clay soils or bedrock, mound septic systems are a default choice, as a conventional system will not work on these sites. Mound septic systems require more sophisticated engineering design than standard systems and need more electrical components and other parts. A mound system consists of a gravel layer on top of a few feet of sand. After installation, topsoil is put over the mound to enable grass planting. The mound system contains distribution pipes set within the gravel level, along with a pump chamber that collects the wastewater emerging from the tank. This pump chamber sends the wastewater into the drain field and should include an alarm system notifying the landowner or a maintenance company if there is a pumping problem.

The useful life of a mound septic system is less than that of a standard septic system. While the latter may need to be replaced every 20 or so years, the mound system may need replacement much sooner than that. Much depends on how well the system is maintained.

A mound septic system requires more frequent inspections and pumping than a conventional system, so these are additional costs to consider. If you have a mound system, you will likely need to have it pumped out annually, compared to a conventional system where you may only need the waste pumped out every two to three years. Of course, much depends on the size of your household. A single person or couple living in a house with a mound system usually won’t need the septic system pumped out as often as a home with a family. While the cost of annual pumping varies by region and the size of the septic system, expect to pay at least a couple of hundred dollars each time the system is pumped. When pumping is added to annual maintenance, expect to pay $500 or more annually in mound septic system care.

There’s another downside to the mound septic system. No one notices a conventional septic system, but with a mound system you’ll have a giant hump in your front or back yard, which doesn’t create a pleasant landscape. Because of the nature of the septic system, you can’t plant trees on the mound, build a patio atop it or place any heavy objects on it. Disguising a mound septic system is difficult if not impossible.