Sanity check here. According to multiple plumbers over the years, I have a sag in the sewer line between my house and the main street line. Water stands there, and eventually enough stuff collects there that we notice slow draining, and have to get it cleaned out with a long snake. We have done this cleanout multiple times over the last decade, with good success.

More recently, we've had gurgling sounds coming from the sink drains in our upstairs master bathroom (but not the other upstairs bathroom), either when they drain, or sometimes when the bathtub drains. There are no signs of restricted drainage elsewhere in the house, including the kitchen and other bath downstairs. Our current plumber (who we like) has repeated the statement that we need to replace that sewer line. If that has to happen now, I'll bite that bullet, but it nags at me that the only symptoms are in the single bathroom upstairs (which, BTW, is directly above where that sewer line leaves the house).

Thoughts? Just don't want to do an expensive sewer line replacement unnecessarily.

1 Answer 1


Gurgling is caused by a partial blockage of either the sewer or the vent. This blockage could be in the main sewer pipe leaving your house, or anywhere in the waste pipes of your house. Likewise with the venting.

Without finding where the blockage is, you cannot say with any certainty that the belly in your sewer is the problem. Video inspection is probably a good idea in your case.

  • And it's conceivable that the gurgling would only happen in certain locations within the house? That's the part that seems odd. Oct 29, 2015 at 1:56
  • Anything upstream of the blockage might gurgle. Anything downstream wouldn't. Opposite is true for vents.
    – Steven
    Oct 29, 2015 at 2:05

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