A Belly in Your Sewer Line: What It Is, How a Camera Finds It, and the Fixes

The short answer

A belly is a low spot in your sewer line, a stretch that sagged lower than the pipe on either side, so water and waste sit in it instead of running out to the street. In Northern Virginia it’s a common find in older lines, and it often turns up when a buyer has the sewer scoped. A shallow belly holding a little water can be left alone and watched. One that holds paper and waste clogs again and again, and the fix is digging up that spot and re-bedding the pipe, or replacing the line. A liner doesn’t fix it.

How a belly happens

• The soil under the pipe settles, often because it wasn’t packed well when the line went in.
• A leaking joint washes soil out from under the pipe over the years.
• The ground shifts from digging nearby: a new driveway, an addition, heavy equipment or another utility line going in.
• Clay soil swells when it’s wet and shrinks when it dries, like the marine clay in parts of Fairfax County, and the pipe moves with it.

Pipe laid in short sections, like clay and cast iron, tends to sag at the joints. A PVC line can belly too, if it was laid on soft fill.

The signs

• The main line clogs, gets cleared, and clogs again, often at the same distance from the cleanout.
• Drains slow down after heavy water use, a load of laundry or a few showers in a row, then recover.
• Toilets gurgle when another fixture drains. Why a toilet gurgles.
• A sewer smell, from waste sitting in the pipe.
• The lowest drain in the house backs up first. Main sewer line clog: the signs.

How a camera finds it

Most of the time a belly leaves no sign on top of the ground. The camera finds it. As it rolls down the line, the picture goes under water where the pipe dips and comes back out on the far side. How much of the pipe is under water, and for how long, tells you how deep and how long the sag is. A transmitter in the camera head lets us stand in the yard with a locator and mark the spot and its depth on the ground, so if it needs digging, the hole goes in one place.

A camera inspection is $89 added to a visit, and you watch the footage with us. When a sewer camera inspection is worth it.

Does a belly need fixing?

Not always. Here’s how we look at it:

• A little standing water, no clogs. Leave it, and look again in a few years or if anything changes.
• Holds water and some waste, clogs once in a while. Keep it clear. A cleaning, or hydro jetting to wash out the low spot, every year or two keeps it running. That’s maintenance, not a fix.
• Holds waste, clogs often, or the pipe at the low spot is cracked or pulled apart. Fix it.

Clearing the main line runs $550 to $1,650 when it does clog. Hydro jetting vs snaking explains why jetting does a better job on a belly than a cable: the cable opens a hole, the water carries the settled waste out.

The fixes

Spot repair. Dig at the marked spot, cut out the sagging section, pack a firm bed of gravel under it so it can’t settle again, set new PVC at the right slope, and connect it to the old pipe on each side. Then the yard goes back.

Replace the line. When there’s more than one belly, or the rest of the pipe is old clay, cast iron or Orangeburg on its way out, replacing the whole run is often the better money. What a new sewer line costs in Northern Virginia has the prices with the monthly payments next to them.

Why lining doesn’t fix it. A cured liner follows the shape of the old pipe. Put a liner in a belly and you have a new, smooth pipe with the same low spot. Lining is great for cracks, root joints and worn pipe that’s still in line, and it’s the wrong tool for a sag. Trenchless sewer repair explains where it fits.

Buying a house with a belly

If the sewer scope on a house you’re buying shows a belly, ask three things: how deep is it, how long is it, and what’s sitting in it. A shallow one with clean water is ordinary wear on an older line. One full of waste, or with a crack at the low spot, is worth a repair price before you close, not after.

A belly is a slow problem. It shows up as clogs that keep coming back and a toilet that gurgles, long before anything backs up. Error codes and warning lights at home covers the other early signs worth knowing.

When you’d rather we do it

A sink clogged at the trap is $99 with our sink clearing offer, up to the P-trap. A toilet, tub, shower or any drain past the trap is drain cleaning, $200 to $800. The main line to the street runs $550 to $1,650, and when grease or roots keep coming back, hydro jetting clears the pipe wall. You get the price before we start. A plumbing diagnosis visit is $49, or $250 after hours.

Call (703) 997-9757, day or night, or see every current deal on our offers page. Rated 5.0 stars across 1,138 reviews on Google, Angi, Yelp, the BBB and Facebook, Virginia Class A license 2705192276.

Questions people ask

What is a belly in a sewer line?

A low spot where the pipe has sagged, so water and waste sit there instead of draining to the street.

How do you know if your sewer line has a belly?

A sewer camera shows it: the picture goes under water at the low spot. Clogs that keep coming back at the same spot are the usual hint.

Is a belly in a sewer line a big deal?

A shallow one with a little water usually isn’t. One that holds waste and clogs often should be repaired.

Can a sewer line belly be fixed without digging?

Not really. A liner follows the old pipe, so it keeps the low spot. The fix is a spot dig and re-bed, or a new line.

Does hydro jetting help a sewer belly?

It washes out the waste that settles there and keeps the line running. It doesn’t lift the pipe, so it’s maintenance, not a fix.