During the inspection on a home we are about to purchase, we filled a whirlpool tub with water in a hallway bathroom. When draining that tub, smelly and dirty water came up in the master bathroom's tub. We assumed it was a blockage. When we brought it to the attention of the current homeowners, they said it was not a blockage, that it was because there is a horizontal run between the two tubs before the vertical drop. And that they didn't do anything about it because they would have had to tear up the walls and ceilings to fix the piping. They then hired a plumber, who said there was a blockage, and he rodded it out, and also changed the drain valve to a slower rate. And now says there is no longer an issue. We are worried that there is an underlying issue with the way the pipes are run.

If the plumber had to reduce the amount of drainage from tub #1 past tub #2 to control a back up even after he snaked them line the he didn't repair anything. All he did was to attempt o reduce the flow from #1 8in hopes it wouldn't back up into #2.
Sounds like faulty plumbing design to me and I'd have the seller make it right. Good luck, Tom

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Originally Posted by speedball1

If the plumber had to reduce the amount of drainage from tub #1 past tub #2 to control a back up even after he snaked them line the he didn't repair anything. All he did was to attempt o reduce the flow from #1 8in hopes it wouldn't back up into #2.
Sounds like faulty plumbing design to me and I'd have the seller make it right. Good luck, Tom

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Thanks Tom, we found out that you were correct. A pipefitter claimed to have fixed the problem but after we re-inspected we found the problem still existed. Is this usually an extremely expensive problem to fix or is it all relative and too many variables to even predict?

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Is this usually an extremely expensive problem to fix or is it all relative and too many variables to even predict?

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It's impossible to advise you without being on site to see for ourselves. This could be as simple as rolling up the tee off the second tubs drain or as complicated as tearing up the floor and redoing the entire run. Sorry I couldn't be more helpful. Tom

Hello Again Tom, The sellers have now agreed to have a plumber come in to "fix" the problem by adding an additional vent. Supposedly this will make it stop backflowing and will make the tub drain at a normal rate. Does this make sense?

It's unlikely the vent will do any good. Tubs have built in vents built into the drain. Poor drain design is the problem. My suggestion would be to get your own plumber to investigate, estimate repair costs, (some floor demo will be needed unless over an open basement) and let the sellers discount that amount to you.

This doesn't sound like a vent problem to me. Sounds more like tub #1 draining into tub#2. I still say that if you had the room to roll the tee on tub #2 up on a 45 and then pick up the trap that would eliminate then back up. Adding a vent won't change the direcxtion of the flow. But let me know if it works, Good luck, Tom