CuthbertRumbold
Jul 25, 2009, 06:17 PM
Hi Plumbing Experts,
Sorry this is pretty long, but I wanted to include as much detail as I could.
I have a problem with (what I'm pretty sure is) a sewer gas odor coming from the 2 sinks in my home. As far as I can tell the smell only occurs when the water is running.
Sink #1 is a bathroom vanity, 2nd floor, fairly old fixture. It has an S-trap then the 1-1/4" drain goes down through the floor, turns to horizontal and empties into the closet bend of the toilet. The toilet drains directly into the main 3" (cast iron) vertical stack, which continues up and out through the roof.
I've gone up to the roof to check the 3" vent. It's clear of any obstructions.
The sink drains pretty freely so I don't suspect a clog, although there is a gurgle sound.
I've looked for signs that the S trap is being siphoned (looking down into the drain with a flashlight), but I can see none. Flushing the toilet produces barely a ripple, and no odor. The odor only appears when running water in the sink.
Sink #2 is the kitchen sink, 1st floor, and the odor here seems less strong, but still present on occasion. This is a single sink and it's pretty new (as is all the associated plumbing). There's no disposal, but there is a connection for the dishwasher on the tailpiece (the dishwasher drain has a high loop; no air gap). The sink trap is a P-trap and it is vented. The trap arm is 1-1/2" and tees into a 2" PVC line, which joins a horizontal 3" main line in the basement. The vent line is 1-1/2" and joins with a 2" vent in the attic.
Again with this sink the trap doesn't seem to be getting siphoned. If I flush a toilet elsewhere in the house, or drain the washing machine, there's only a ripple in the water in the trap. And no odor. I think the vents are OK. But if you run the water in this sink you will occasionally get a whiff of odor here too.
Is there some way that a 'bubble' of gas can come up through the (P or S) trap while water is flowing down? This seems to be what's happening.
It occurred to me that the smell might be the water itself, but I don't think so. If I pour a glass of water and take it away from the sink for a sniff there's no apparent odor.
Any ideas? I'm flummoxed.
Thanks!
Roy
Sorry this is pretty long, but I wanted to include as much detail as I could.
I have a problem with (what I'm pretty sure is) a sewer gas odor coming from the 2 sinks in my home. As far as I can tell the smell only occurs when the water is running.
Sink #1 is a bathroom vanity, 2nd floor, fairly old fixture. It has an S-trap then the 1-1/4" drain goes down through the floor, turns to horizontal and empties into the closet bend of the toilet. The toilet drains directly into the main 3" (cast iron) vertical stack, which continues up and out through the roof.
I've gone up to the roof to check the 3" vent. It's clear of any obstructions.
The sink drains pretty freely so I don't suspect a clog, although there is a gurgle sound.
I've looked for signs that the S trap is being siphoned (looking down into the drain with a flashlight), but I can see none. Flushing the toilet produces barely a ripple, and no odor. The odor only appears when running water in the sink.
Sink #2 is the kitchen sink, 1st floor, and the odor here seems less strong, but still present on occasion. This is a single sink and it's pretty new (as is all the associated plumbing). There's no disposal, but there is a connection for the dishwasher on the tailpiece (the dishwasher drain has a high loop; no air gap). The sink trap is a P-trap and it is vented. The trap arm is 1-1/2" and tees into a 2" PVC line, which joins a horizontal 3" main line in the basement. The vent line is 1-1/2" and joins with a 2" vent in the attic.
Again with this sink the trap doesn't seem to be getting siphoned. If I flush a toilet elsewhere in the house, or drain the washing machine, there's only a ripple in the water in the trap. And no odor. I think the vents are OK. But if you run the water in this sink you will occasionally get a whiff of odor here too.
Is there some way that a 'bubble' of gas can come up through the (P or S) trap while water is flowing down? This seems to be what's happening.
It occurred to me that the smell might be the water itself, but I don't think so. If I pour a glass of water and take it away from the sink for a sniff there's no apparent odor.
Any ideas? I'm flummoxed.
Thanks!
Roy