Signs your main sewer line is clogged

The clearest sign of a main sewer line clog is more than one drain acting up at the same time. You flush a toilet and water comes up in the tub, or the toilet gurgles while the washer drains. If that’s happening, stop using water in the house and call a plumber. Every gallon you send down has nowhere to go except back up through your lowest drain.

How do I know it’s the main line and not one drain?

A single slow sink is almost always a local clog. The main line is the big pipe that carries everything from your house out to the city sewer or your septic tank. When it’s blocked, the symptoms show up all over the house. Watch for these:

• Several fixtures draining slowly at once, especially on the lowest floor
• A toilet that gurgles or bubbles when the washer drains or a sink empties
• The tub or shower filling with water when someone flushes
• Dirty water coming up in the lowest drain in the house, usually a shower, a tub, or a floor drain
• A sewage smell that won’t go away
• Wet spots in the yard, or a strip of grass over the sewer line that’s greener and thicker than the rest

If it’s only the kitchen sink or one bathroom, start with what’s worth trying on a slow drain. And a smell with no slow drains usually has a different cause. See why your house might smell like sewer.

Sewage coming up? Stop running water. Don’t keep flushing to push it through. Shut off the dishwasher and the washing machine, and tell everyone in the house to hold off on water until the line is clear. You can call us any time for an emergency, and this counts.

What causes a main sewer line to clog?

• Tree roots. Roots go after the moisture in sewer lines and work their way in through joints and small cracks. Once they’re inside, they grow into a net that catches everything else.
• Grease. Cooking grease goes down as a liquid, then cools and hardens along the pipe walls. It builds up over years.
• Wipes, including the ones labeled “flushable.” They don’t break apart the way toilet paper does, and they snag on roots and rough spots.
• A sagging or broken pipe. When a section of line settles into a low spot, plumbers call it a belly. Waste sits there and piles up.
• Old pipe. Huntsville grew fast in the 1950s and 60s, and houses from that era often have cast iron drains. Cast iron rusts and scales on the inside until the opening gets smaller. Older sewer lines in the yard are often clay, and roots love the joints in clay pipe.

What does a plumber do about it?

First, get the water moving. A plumber will usually go in through a cleanout, which is a capped pipe that gives straight access to the main line. It’s often outside near the foundation, or in the crawlspace or garage. From there, a sewer machine with a cutting head bores through the blockage. Some lines call for water jetting, which blasts the pipe walls clean with high-pressure water.

Then find out why it clogged. A camera run down the line shows whether it was a one-time grease plug or roots coming through a cracked joint. That matters, because roots grow back. If the pipe is broken or has a belly, clearing it buys you time, and the real fix is repairing that section.

If you know where your cleanout is, don’t pull the cap while the line is backed up. Whatever’s sitting in that pipe can come out under pressure, and it’ll land on you.

Skip the chemical drain cleaner here too. It won’t reach a main line clog, and it leaves a mess of caustic water for whoever has to open the line.

Whose sewer line is it?

In Huntsville, the City says the sewer service line running from your house to the main sewer is the customer’s responsibility. So a clog or break anywhere between your house and the city main, including under your yard, is yours to fix. Madison, Decatur, and Athens are usually similar, but check with your city or utility to be sure.

If there’s damage inside the house from a backup, call your insurance company and ask what your policy covers. Sewer backup coverage varies a lot.

What if you’re on septic?

On septic, the signs look almost the same. The cause is often different. A backup on a septic system is frequently a tank that’s overdue for pumping, or a blocked line between the house and the tank.

Most septic tanks need pumping every few years, depending on the tank size and how many people live in the house. If yours hasn’t been pumped in a long time, that’s the first call to make. If it was pumped recently, the line from the house to the tank is the next suspect.

Either way, don’t wait on a main line backup. It gets worse with every flush.