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When I flush my toilet it makes a very loud rumbling noise that can be heard from other rooms, what could cause this?

  • The sound cannot be heard from the bathroom.
  • There is no sound when the tank is filling, only just as the toilet flushes.
  • The toilet sits just off the main stack, by way of a Y connection.
  • The sound is mostly audible from the side of the house where the kitchen is, and not from the other side of the house.
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2 Answers

From your comments, my guess is this is vibration of the drain line, and/or the vent stack, heard through the wall. I'll bet that one of those lines is not secured tightly, so you hear vibration in the wall to the kitchen. The vent stack may be touching the drywall in the kitchen, so you hear it "rumbling" in there, but not in the bathroom itself.

If you have access to this area in the basement, have someone stand down there with their hands tightly grasping the offending drain line/stack. The idea is to see if you can muffle the sound by dampening the vibration.

If this works, then the solution will depend on how well you can reduce those vibrations. Insulation might help, if you can stuff it up into the wall cavity next to the stack. Tie down the drain itself to nearby joists.

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Funny thing is the stack runs up the wall on the opposite side of the house from where the noise is. –  Tester101 Nov 10 '10 at 14:08
    
@tester101: is there anything plumbing-related in the wall where you hear the noise? –  Niall C. Nov 10 '10 at 14:16
    
No, it's a one story house so all the plumbing is in the basement. I could understand the noise if the toilet drain ran under the floor in that part of the house or something, but the drain is connected directly to the main sewer line (Straight down). –  Tester101 Nov 10 '10 at 14:23
    
@tester101: What about the water main and sewer? Do they go anywhere near the area where the noise can be heard? –  Niall C. Nov 10 '10 at 14:34
    
No, water main and sewer line are at the other end of the house. –  Tester101 Nov 10 '10 at 15:48
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up vote 3 down vote accepted

Turns out the loud noise was caused by water rushing from other fixtures. The house had galvanized steel pipe as the main feed line (off the meter) which had become restricted, so when the toilet could not pull enough water from the main line it sucked it from other lines.

Replacing the galvanized pipe fixed the issue (as well as increased the pressure to the entire house).

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how'd you figure it out? –  Michael Pryor Jun 16 '11 at 0:05
    
@Michael: I planned to update the galvanized pipe anyway, and I finally got around to doing it. It's been 3 weeks, and I have not heard the noise since I updated the plumbing. I had a hunch that was what was happening, since I heard the noise on the other end of the house. –  Tester101 Jun 16 '11 at 1:44
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