Sand Mound Septic Systems: A Guide for Bucks County Homeowners
If your septic drain field looks like a long, grassy hump in the yard, you probably have an elevated sand mound. Mounds work well, but they have a few more parts than a standard in-ground system, so they need a little more care. Here’s how they work, how to look after one, and what to do when something goes wrong.
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What Is a Sand Mound Septic System?
Like any septic system, a mound starts with a septic tank that holds back solids. The difference is where the wastewater goes next. Instead of soaking into trenches dug into the natural soil, it’s spread through pipes in a bed of gravel that sits on a layer of sand built up above the ground and covered with soil and grass.
Pennsylvania lists the elevated sand mound as one of its standard on-lot system types, and the design rules are set in state regulations (25 Pa. Code § 73.55). A few of those rules explain what you see in the yard:
- The mound must provide at least 4 feet of suitable material between the bottom of the gravel and the “limiting zone” below it, such as bedrock or a seasonal high water table.
- There must be at least 1 foot of sand under the gravel.
- The mound is wrapped in a soil berm and topped with at least 1 foot of soil that can grow grass.
- Mounds are only allowed on ground with a slope of 12% or less.
Why Some Homes Need a Mound
Wastewater needs enough clean soil to filter through before it reaches rock or groundwater. When a soil test shows that rock or a high water table is too close to the surface for an in-ground system, building the absorption area up with sand is one of the approved ways to get that depth. Whether a lot needs a mound is decided by the site evaluation and permit, not by the homeowner.
The Parts of a Mound System
Because the mound sits higher than the septic tank, wastewater usually can’t flow there by gravity. As Penn State Extension explains, the big difference from a conventional system is a pumping station that delivers wastewater to the mound at intervals. A typical setup has:
- The septic tank, where solids settle out.
- A pump tank (also called a dosing tank) with a pump and float controls.
- A pressure line and small distribution pipes that spread each dose across the mound.
- The mound itself: gravel, sand, berm and grass cover.
That pump and its electrical controls are the parts a conventional gravity system doesn’t have, and they’re worth knowing about. If your system has an alarm panel, find it now so you’ll recognize it if it ever goes off.
How to Take Care of a Sand Mound
The Pennsylvania Department of Environmental Protection’s septic system guidance applies to mounds too. In practice, that means:
- Keep vehicles and heavy equipment off the mound. DEP advises keeping heavy vehicles, equipment and livestock away from the whole septic system. Compacting the sand or berm can damage it.
- Keep grass on it, not trees or shrubs. DEP warns against planting trees and shrubs over or close to the system, since roots can reach the pipes.
- Send roof and yard water elsewhere. Point downspouts, sump pump discharge and runoff from paved areas away from the mound.
- Spread out water use. Conserving water and not running several loads of laundry back to back puts less strain on the pump and the mound.
- Keep chemicals and bulky waste out. Grease, harsh chemicals, wipes and other slow-to-break-down items belong in the trash.
- Keep records. DEP recommends keeping the system’s design, location, inspection, pumping and repair records together. A buyer will ask for them when you sell.
How Often Should a Mound System Be Pumped?
DEP’s general advice is to have the septic tank pumped at least every 3 to 5 years, depending on tank size and household size, and to inspect the tank, pipes and absorption area every year. Many Bucks County townships also have their own sewage management rules that set a pumping schedule and require the report to be filed. Those rules vary by township, so check with yours. Our septic tank pumping page covers what happens during a pump-out.
With a mound, it’s worth asking the pumper to look at the pump tank and alarm during the same visit, not just the main tank.
Signs Your Mound Needs Attention
- The pump alarm is sounding or its light is on.
- Wet, spongy spots or seepage on the sides or at the toe of the mound.
- Sewage odors near the mound or the tanks.
- Slow drains or gurgling in the house.
- Erosion, bare patches or settling on the mound.
If you see any of these, cut back on water use and have a septic professional take a look. See our septic repair and drain field page for what a diagnosis usually involves.
Repairs, Replacement and Permits in Bucks County
Some mound problems are simple fixes, like a failed float or pump. Others, like a saturated mound, may need a bigger repair or a replacement. In Bucks County, the Bucks County Health Department’s Sewage Program permits new and repaired septic systems and helps property owners with malfunctioning systems. Your septic professional can tell you whether your repair needs a permit.
What Affects the Cost of Mound Work?
We don’t post prices, because every property is different. The main factors are:
- The type of work: routine pumping, a pump or float replacement, or a full mound repair or rebuild.
- Access to the tanks and the mound, and whether lids need to be dug up.
- Site conditions found during evaluation, such as soil and slope.
- Permits and design work if the system has to be repaired or replaced.
Sand Mound FAQ
Can I put a shed, patio or garden on my mound?
No. Structures, paving and heavy use can compact or damage the mound. Keep it in grass.
Can I mow the mound?
Yes, keeping the grass cover healthy is part of the job. Use a light mower and avoid driving heavy equipment over it.
What should I do if the alarm goes off?
Cut water use right away and call a septic professional. The pump tank has only limited room before it backs up.
I’m buying a home with a sand mound. What should I check?
Ask for the permit and pumping records, and get a septic inspection that includes the pump tank and controls. See our septic inspection page for what’s usually covered.
Need Help With a Sand Mound?
Request a quote online and a local septic professional will follow up by email, or call 215-770-8510 if you prefer. We serve Quakertown, Perkasie, Sellersville, Doylestown, New Hope, Chalfont and Dublin. For more, see the Bucks County Septic Guide.
This guide is general information, not a substitute for advice from a licensed septic professional or your township’s Sewage Enforcement Officer. Last reviewed October 2026. Bucks County Septic connects homeowners with independent local septic service providers.