Main Sewer Line Clog: The Signs, What to Do Right Now, and What It Costs

The short answer

Your main sewer line is the one pipe that carries everything from the house out to the street. When it clogs, the whole house feels it: more than one drain slows down, toilets gurgle, and water comes up at the lowest drain in the house, often the basement floor drain or a basement shower. In Northern Virginia, clearing the main line runs $550 to $1,650. The first thing to do is stop running water, all of it, until it’s cleared.

Signs it’s the main line, not one drain

One slow sink is a sink problem. These point at the main:

• Two or more fixtures are slow or backing up at the same time, especially on different floors.
• The lowest drain backs up first. Water finds the lowest opening on the line, so a basement floor drain, basement shower or first floor toilet shows it before anything upstairs.
• Water from one fixture shows up in another: the tub fills when the toilet flushes, or the floor drain bubbles when the washer drains.
• Toilets gurgle, or the water in the bowl rises and drops on its own. Why a toilet gurgles.
• A sewer smell from the drains. What a sewer smell in the house means.
• Water standing in the cleanout pipe outside when you take the cap off.

Not sure which you have? Is it one drain or the main line? walks through a five minute test.

What to do right now

1. Stop using water. Tell everyone in the house: no flushing, no showers, no dishwasher, and most of all no washing machine. A washer pumps out a lot of water fast, and that’s what turns a partial clog into a backup.
2. Don’t pour in chemical drain cleaner. It can’t reach a clog that far down the line, and it sits in the pipe waiting for whoever opens it next.
3. Find the cleanout, a capped pipe sticking out of the ground near the foundation, or a capped fitting on the drain line in the basement. Where your sewer cleanout is shows what to look for.
4. If it’s outside, loosen the cap slowly with a wrench, standing to one side. If the pipe is full of water, the clog is between there and the street. If it’s dry, the clog is between the cleanout and the house. Either way, that’s useful to tell the plumber. Don’t open a cleanout inside the house during a backup.
5. Call. A main line clog doesn’t clear itself, and every flush adds to what’s sitting in the pipe.

What causes it

• Wipes, including the ones sold as flushable. They don’t break down like toilet paper and they snag on anything rough. Paper towels, floss and feminine products do the same. What never goes down a drain.
• Grease from the kitchen that cools and sticks along the pipe, then catches everything else. Holiday cooking is the classic one: holiday kitchen drain clogs.
• Tree roots in the joints of older clay, cast iron and fiber lines. Tree roots in your sewer line.
• A belly, a low spot where the pipe sagged and now holds water and waste. A belly in a sewer line.
• A pipe that’s cracked, shifted or flattening with age. Orangeburg pipe and cast iron drain pipe cover the two most common in older Northern Virginia houses.

Should you rent a drain machine?

You can, and some people do. A rented main line machine spins a heavy cable hard, and it bites back: the cable can whip, kink or wrap around itself, and it can hurt a hand in the wrong place. It can punch a hole through roots or wipes without clearing them, so the line backs up again in a week. And it can get stuck in an old pipe, which turns a clog into a dig. If you’ve run one before and the pipe is PVC, fine. On an old line nobody has ever put a camera in, we’d skip it. How to use a drain snake covers what a hand snake can reach.

What it costs

Clearing the main line runs $550 to $1,650 in Northern Virginia. Where it lands depends on how we get in (an outside cleanout is the easy way, pulling a toilet or going through the roof vent takes longer), how far down the clog is, and what it is. You get the price before we start.

A camera down the line is $89 added to the visit, and it’s worth it the second time a main line clogs, because the camera tells you why. If grease or roots keep coming back, hydro jetting cleans the pipe wall instead of just opening a hole through the middle.

When it’s already backed up

If sewage is already on the basement floor, it’s a cleanup as well as a clog. Stay out of the water, keep kids and pets away, and don’t run anything. Sewer backup in the basement walks through what to do first. A backed up main is one of the loudest warning lights a house has, and error codes and warning lights at home covers the quieter ones that come before it.

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

How do I know if my main sewer line is clogged?

More than one drain is slow at once, toilets gurgle, and water comes up at the lowest drain in the house, often the basement floor drain or a basement shower.

What does it cost to clear a main sewer line in Northern Virginia?

Clearing the main line runs $550 to $1,650, depending on access, distance and what the clog is. A camera inspection is $89 added to the visit.

Can I clear a main line clog myself?

Sometimes, with a rented machine, if you’ve run one before and the pipe is in good shape. On an old line it can get stuck or punch through without clearing it.

Will a main sewer line clog clear on its own?

No. Water and waste keep piling up behind it, so stop using water and get it cleared.

Who fixes a clog in the sewer under the street?

The public sewer is your sewer utility’s job, like Fairfax County, Arlington County, Loudoun Water or Prince William Water. The line from the house to the public sewer is usually the homeowner’s.