House is on septic system. Tank is on north side of house but underground. Cleanout for the line to tank is also on the north side of the house. Sewer odors are only smelled when there is a north wind. 2 bathrooms. We have narrowed it down to the sewer smell only comes from shower/tub drainlines. Not the bathroom sinks, not laundry, not kitchen sink. We have tried everything. First we extended the roof vents higher, didn't work. Then we removed the vents from the roofline which was also on the north side of the house and replaced them with attic studer valves. Attic is well ventilated and has excellent air turnover. Then both bathrooms were remodeled and we found in both bathrooms that the p-traps were placed after the vent lines improperly on the tub/showers. Figured this was the problem since the sinks in the house all had p-traps under the basin which is why they weren't smelling. After both bath remodels with shower/tub p-traps and plumbing done to code, still getting the odor only when north wind blows. Only other thing we can think of is maybe doing a backflow preventer in the 4" line exiting the house to the septic tank but don't want to do that unless necessary. Any other ideas on how the odor is coming in?
sewer odor
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additional info: After south side bath was remodeled 2 years ago, it no longer stunk and the smell came from the north bath only which we thought confirmed that it was the p-trap issue. Kept the north tub/shower combo drain covered and overflow plugged if the north wind blew. Just remodeled the north bath and installed p-traps to code. Old bath had the stinky tub/shower combo and now tub and shower are separate. Tub is using old sink vent line and I think the new shower vent line is combined with new sink vent line in the attic. Just using my nose, I don't think any odor is coming from the new tub drain or the the new sink drains, but only from the shower drain. South bath still does not stink. I will clarify with contractor if shower vent is separate from sink vent. If it is, maybe the airflow in the attic during a north wind only affects that vent due to its placement in the attic, but the studer valve still should prevent that happening whether it is by itself or combined with the sink vents
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The only time you get gas up the pipe is when there is not enough water in the trap.
The wind would not effect a studer valve. When you smell it do you dribble water down the drains to confirm they are full. If adding water makes it go away, does it come back when you flush the toilet?
Are using nat gas or propane for anything in the house?
The wind would not effect a studer valve. When you smell it do you dribble water down the drains to confirm they are full. If adding water makes it go away, does it come back when you flush the toilet?
Are using nat gas or propane for anything in the house?
I ran water just to make sure p-trap was full, still smelled
Toilet flush does not affect it (that I can tell) since the bathroom just smells like methane overall. Toilet is right next to shower and I haven't noticed a surge of smell when flushing
House is all electric, no gas or propane
The ONLY thing that affects it is a north wind. Zero smell when winds are any other direction. Smell increases the stronger the north wind is
Toilet flush does not affect it (that I can tell) since the bathroom just smells like methane overall. Toilet is right next to shower and I haven't noticed a surge of smell when flushing
House is all electric, no gas or propane
The ONLY thing that affects it is a north wind. Zero smell when winds are any other direction. Smell increases the stronger the north wind is
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Go you have a crawl space, How far from the house is the septic field?
Full Basement. all plumbing under floor joists. No plumbing additional plumbing in basement except sump pump in northeast corner of basement
Lagoon is located about 200ft to the north east of the house. This shower is in the northwest corner of the house
Septic tank is buried about 15' directly north of the middle of the house with its main inlet line clean out about 1' from the house, again at the middle of the house
Tank was pumped about 3 months ago, this problem has been going on for years.
Lagoon is located about 200ft to the north east of the house. This shower is in the northwest corner of the house
Septic tank is buried about 15' directly north of the middle of the house with its main inlet line clean out about 1' from the house, again at the middle of the house
Tank was pumped about 3 months ago, this problem has been going on for years.
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I would be suspect of disconnected vent pipe in a wall somewhere.
Plastic or cast iron pipe?
asked ccntractor and all bath fixtures are separately vented with studers. House was built in 1999 with PVC vents. Master bath (where smelly shower drain is) was taken down to the studs during remodel and no unused vent pipes and none seen in the attic. Other bath (on south side) remodeled 2 years ago and bath/shower was also taken down to the studs except for behind sink. That bath did smell before remodel but has no odor now. Both baths had improperly placed p-traps on tub/shower combo which is why we thought the problem would be fixed with the remodels. Now only the new shower drain has smell and only when north winds. For the many years this has been a problem it has ALWAYS only occurred when north wind blows. Prevailing north winds here typically come from the NW or directly N. Rarely NE
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Do the toilets vent thru the roof?
toilets vent to the attic now (not roof) and each has a studer valve. Originally years ago, when smell was still a problem, all plumbing vented to the roof. We tried all that first. First we extended all the vent pipes thinking maybe with a north wind, there was some sort of eddying with the roof. That didn't solve the problem, so then we cut the vents off in the attic and replaced with studer valves hoping that would fix it. Did not. Then when p-traps were noticed installed after the vent (drain, then vent, then p-trap) in both baths in both tub/shower units (and both baths stunk bad back then with north winds), we figured that was the problem. Did fix it in the south bath that was remodeled 2 years ago, no odor there now. But north bath just fully remodeled last month, only shower drain now stinks.
Contractor says every vent pipe in attic is separate and has it own studer valve.
He asked about any exposed pipe from house to septic to lagoon where when the winds are strong enough, it could be pushing the gases past the shower p-trap. I responded to him this...."the outlet pipe from the house to the septic is underground as well as the pipe from the tank to the lagoon. The ONLY open possibility to that closed system is a clean out pipe that is located on the north side of the house about 1' from the house at the kitchen sink area. I've sometimes wondered if this pipe is the problem. However, why would only the shower drain get the smell if it can get past that p-trap, why not all of them"
Contractor says every vent pipe in attic is separate and has it own studer valve.
He asked about any exposed pipe from house to septic to lagoon where when the winds are strong enough, it could be pushing the gases past the shower p-trap. I responded to him this...."the outlet pipe from the house to the septic is underground as well as the pipe from the tank to the lagoon. The ONLY open possibility to that closed system is a clean out pipe that is located on the north side of the house about 1' from the house at the kitchen sink area. I've sometimes wondered if this pipe is the problem. However, why would only the shower drain get the smell if it can get past that p-trap, why not all of them"
we have considered putting a back flow valve in the main 4" line that exits the house to the septic in the basement. Didn't want to add anything that if it sticks in the future, it could cause a back up in the house and would like to keep the system as simple as possible, but that may be a last resort. Or could check the standing clean out pipe. Maybe previously homeowner hit it with a lawnmower and cracked it.
Proper traps and sealed pipes should be preventing any smell from getting into the house.
Toilets are an open trap so you can see if they are filled. Where the toilet is sealed to the floor it can leak, wax seal.
When a vent line is obstructed the exiting water can siphon the trap below being blocked. Has anyone inspected all vent lines, there are long thin cameras to do that.
Note, you need to be mapping out the entire vent/drain system. keep notes and sketches on all work done. Being a long term problem points to something done wrong from the start, pipe not connected or not connected properly.
Bud
Toilets are an open trap so you can see if they are filled. Where the toilet is sealed to the floor it can leak, wax seal.
When a vent line is obstructed the exiting water can siphon the trap below being blocked. Has anyone inspected all vent lines, there are long thin cameras to do that.
Note, you need to be mapping out the entire vent/drain system. keep notes and sketches on all work done. Being a long term problem points to something done wrong from the start, pipe not connected or not connected properly.
Bud
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A backflow valve will not help with this problem. They are designed to stay fully open except if liquid (only liquid) starts to flow backward to the normal flow direction.
You didn’t mention if the basement is finished. If it isn’t can you give us some photos of the drain piping for the north bathroom shower, which you believe is the only problematic fixture now.
How confident are you that the north bathroom shower drain is the source of the smell? This should be easy to determine by putting something airtight over the drain on a day when the wind is blowing from the direction that causes the problem.
Does your basement sump have a vent line that runs inside the wall, into the attic and through the roof?
Have you followed the sewage drain line backwards from the point where it enters the basement floor looking for any unexplained connections that might have been placed there by the original installer in anticipation of some future development? If there were an uncapped drain line buried in the north wall it might not leak liquid, but it could allow noxious gases to build up in the wall cavity which might then pushed into the interior of the house by a north wind.
Chris
You didn’t mention if the basement is finished. If it isn’t can you give us some photos of the drain piping for the north bathroom shower, which you believe is the only problematic fixture now.
How confident are you that the north bathroom shower drain is the source of the smell? This should be easy to determine by putting something airtight over the drain on a day when the wind is blowing from the direction that causes the problem.
Does your basement sump have a vent line that runs inside the wall, into the attic and through the roof?
Have you followed the sewage drain line backwards from the point where it enters the basement floor looking for any unexplained connections that might have been placed there by the original installer in anticipation of some future development? If there were an uncapped drain line buried in the north wall it might not leak liquid, but it could allow noxious gases to build up in the wall cavity which might then pushed into the interior of the house by a north wind.
Chris
basement is half finished. The finished bedroom under the problem bathroom has a suspended ceiling so plumbing was all uncovered and visable during remodel. No unusual piping. Both contractor and a certified plumber were up under there so I have confidence they did it right and didn't find anything weird.
Other bathroom had the basement finished ceiling under the tub/shower unit opened up to fix the p-trap. Only plumbing fixture not seen or be able to be seen is the sink drain in the other bath which has never had an odor and never had a problem draining.
Kitchen sink, laundry and sump pump are all in the unfinished basement and no extra or weird piping.
Not sure about the sump pump having a vent or not. Have to look into that.
I have a cursed nose, very sensitive and unfortunately can detect specific body odors from several feet away. I trust it that it is the shower drain emitting the odors as I put my nose into the tub and sink drains and smelled nothing. I covered the shower drain with a towel and the odor decreased tremendously, so confident in that also
Contractor had a good idea. Next north wind, cover the outside clean-out pipe with a trash bag and see if the problem goes away. Since it is so affected by the wind (I have zero odors..again the good nose tells me so....if there is not a north wind), he thinks the wind is entering from the north into the septic system somewhere (which is all located on the north side of the house) and creating such a pressure differential that it is blowing the gases past the shower drain p-trap (even when the p-trap has water in it) and it is affecting the north shower drain as that is most likely the path of least resistance. Easy to try and would rule out the clean out pipe as the problem or not. Clean out is right next to the house and an opening/crack in it would be the best place for pressure to enter the house. Something after the tank (which is all buried except the actual lagoon) would lose some of its pressure in the open space above the fluid in the tank.
Other bathroom had the basement finished ceiling under the tub/shower unit opened up to fix the p-trap. Only plumbing fixture not seen or be able to be seen is the sink drain in the other bath which has never had an odor and never had a problem draining.
Kitchen sink, laundry and sump pump are all in the unfinished basement and no extra or weird piping.
Not sure about the sump pump having a vent or not. Have to look into that.
I have a cursed nose, very sensitive and unfortunately can detect specific body odors from several feet away. I trust it that it is the shower drain emitting the odors as I put my nose into the tub and sink drains and smelled nothing. I covered the shower drain with a towel and the odor decreased tremendously, so confident in that also
Contractor had a good idea. Next north wind, cover the outside clean-out pipe with a trash bag and see if the problem goes away. Since it is so affected by the wind (I have zero odors..again the good nose tells me so....if there is not a north wind), he thinks the wind is entering from the north into the septic system somewhere (which is all located on the north side of the house) and creating such a pressure differential that it is blowing the gases past the shower drain p-trap (even when the p-trap has water in it) and it is affecting the north shower drain as that is most likely the path of least resistance. Easy to try and would rule out the clean out pipe as the problem or not. Clean out is right next to the house and an opening/crack in it would be the best place for pressure to enter the house. Something after the tank (which is all buried except the actual lagoon) would lose some of its pressure in the open space above the fluid in the tank.
You said, "" Both contractor and a certified plumber were up under there so I have confidence they did it right and didn't find anything weird.""
Unidentified smell coming from unidentified place, I wouldn't assume anything done right until it's found.
Unidentified smell coming from unidentified place, I wouldn't assume anything done right until it's found.
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Studor valves (air admittance valves) have only half the functionality of an “open to atmosphere” vent pipe. That’s one of the reasons that most plumbing codes restrict their use to very specific installations where normal vent piping is impractical, like a sink located in a kitchen island. The many Studor valves installed in your house may be contributing to the problem rather than helping to solve it.
When the toilet is flushed in the diagram that I’ve attached a slug of fluid starts to travel from left to right, lowering the air pressure behind it and raising the air pressure in front of it. With a normal vent pipe (the red double-ended arrow), that increased air pressure in front of the slug pushes some air up the vent pipe and out the vent outlet on the roof. Once the slug passes the junction with the vent the air pressure is lowered and air flows into the vent pipe to follow the slug down the pipe. If a Studor valve is installed instead, that double-ended red arrow gets replaced with the blue one pointing down only, since the valve only allows air in, not out. So when the toilet is flushed and the slug of water starts to travel down the pipe towards the junction with the vent pipe, the air pressure goes up in front of the slug and the only place for it to escape is past the water seal in the sink trap. Depending on the sizes and lengths of pipe involved this may or may not actually happen, but this illustrates why Studor valves shouldn’t be used without a really good reason.
Imagine the worst case scenario where every vent pipe in a house has been replaced with a Studor valve (as I read that has been done in your house), creating a drain system with no way to release pressure, like when a bathtub of hot water is drained away, heating and expanding all the gas in the closed system to the septic tank. The only place for that pressure to be released (by “burping” sewer gas) would be through a trap somewhere.
Chris
When the toilet is flushed in the diagram that I’ve attached a slug of fluid starts to travel from left to right, lowering the air pressure behind it and raising the air pressure in front of it. With a normal vent pipe (the red double-ended arrow), that increased air pressure in front of the slug pushes some air up the vent pipe and out the vent outlet on the roof. Once the slug passes the junction with the vent the air pressure is lowered and air flows into the vent pipe to follow the slug down the pipe. If a Studor valve is installed instead, that double-ended red arrow gets replaced with the blue one pointing down only, since the valve only allows air in, not out. So when the toilet is flushed and the slug of water starts to travel down the pipe towards the junction with the vent pipe, the air pressure goes up in front of the slug and the only place for it to escape is past the water seal in the sink trap. Depending on the sizes and lengths of pipe involved this may or may not actually happen, but this illustrates why Studor valves shouldn’t be used without a really good reason.
Imagine the worst case scenario where every vent pipe in a house has been replaced with a Studor valve (as I read that has been done in your house), creating a drain system with no way to release pressure, like when a bathtub of hot water is drained away, heating and expanding all the gas in the closed system to the septic tank. The only place for that pressure to be released (by “burping” sewer gas) would be through a trap somewhere.
Chris
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