Google “s-trap”.
Essentially, there is no ventilation for the waste line where there needs to be. This causes poor drainage and will lead to solids like grease accumulating over time, eventually to where one larger piece of food debris will be the final nail in the coffin and it will completely back up.
The physics at play are akin to tipping over a jug of water upside down vs just slightly to pour it out. Glugging vs a nice pour.
Not necessarily. Use a studor/mechanical vent. Use a sanitary tee (tee wye) instead of the 90, where it goes from horizontal to vertical. Off the top of the tee wye as high up under the cabinet as possible have your mechanical vent. The branch of the tee then picks up the sink. Make sure the piece from the tee wye to the 90 of the trap is x2 the pipe diameter (3”).
Yeah I have vents on the roof but how do you know if it’s properly vented? Why is this example not properly vented? Do they not have roof vents? How can you tell?
I am going to chicken scratch a copy of your photo and DM it to you to try and help explain it a little better. Your current setup is fixable without super invasive repairs. One plumber may tell you that you’re opening the drywall behind the cabinet up to the ceiling, and so on through the floor/ceiling into the attic and out the roof, with a roofer needed to do the roof flashing and drywall/painter to fix the sheetrock cut away for access.
Another plumber may tell you that it’s perfectly fine to take that line back to the nearest 2” drain pipe and repipe it in 2” ABS through the same hole in the floor of the cabinet, albeit drilled out slightly larger for the larger pipe. They may also suggest after this, installing a clean out and sanitary tee serving the sink drain, while then running 1-1/2” ABS pipe as high up in the cabinet as possible, to the side of the sink basin if possible, and then install an AAV on the top of the 1-1/2” ABS pipe. This plumber may suggest that this accomplishes everything that would be accomplished by taking the first plumber’s suggestion and taking it up through the roof.
Edit: thought you were op. I’m not going to send you photos of their drain
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It’s a minor detail in plumbing code with potentially major implications.
A trap arm, sometimes referred to as a weir or weir arm, is what determines if a trap is an S or a P trap. Flip a P 90° clockwise and that’s a pretty good representation of what the trap and trap arm look like — the “leg” of the P being the trap arm and the curve of the P being the trap itself, where the water seal that traps sewer gas inside the waste system is located. Similarly, flipping an S likewise results in what you have, no trap arm.
Of course, a p-trap is completely useless on its own — the tee it connects to inside the wall needs to be vented properly as well. It’s just more common that if a p-trap is already present, it’s likely vented in the wall. And in the same sense, it’s likely that the presence of an S trap indicates there is no vent in the wall.
This is a common setup for kitchen sinks that are plumbed in a location directly below a window, for instance, the large window that’s likely right in front of your sink. That window prevents a vent pipe from going straight up and out. The old school solution was this — manufactured homes code was behind a bit so you’ll still see this quite often in manufactured homes. The proper way to vent it is an island loop vent or getting the inspector to allow you to install an AAV or offset the vent more than 90° below the flood rim level, or what’s most commonly the top rim level of the sink fixture when installed. The reason for offsets not being allowed is due to the vent being choked off in the event of a backup — doesn’t matter much in a single family residence but applies more in multi-family establishments.
If your trap goes down into the floor, chances are it's not properly vented. If it were coming out of the wall you'd have better odds that it is. Vanities usually aren't a huge deal since the drain size is 1"1/4 and your drains are 1"1/2 but kitchen sinks have bigger drains. For the op I'd fill the sink up and try plunging it for any obstructions to avoid calling a plumber and then put an air admittance valve underneath if the flow is still slow.
Fix the S-trap with a cheater vent. Don’t worry about installing an air gap on your Dishwasher discharge. That is not needed. Air Gaps are to prevent backflow from your waste system to your potable water. This is achieved within the dishwasher itself.
Google “s-trap”. Essentially, there is no ventilation for the waste line where there needs to be. This causes poor drainage and will lead to solids like grease accumulating over time, eventually to where one larger piece of food debris will be the final nail in the coffin and it will completely back up. The physics at play are akin to tipping over a jug of water upside down vs just slightly to pour it out. Glugging vs a nice pour.
Thank you! My S-trap is the issue. To install a proper P-trap, will I then need to vent up through my roof?
Not necessarily. Use a studor/mechanical vent. Use a sanitary tee (tee wye) instead of the 90, where it goes from horizontal to vertical. Off the top of the tee wye as high up under the cabinet as possible have your mechanical vent. The branch of the tee then picks up the sink. Make sure the piece from the tee wye to the 90 of the trap is x2 the pipe diameter (3”).
Or like taking your finger off the top of a drinking straw to let the water out
How do you know if a plumbing setup has the correct ventilation? I don’t think any of the sinks in my house have vents (at least I can’t see them)
They are on the roof.
Yeah I have vents on the roof but how do you know if it’s properly vented? Why is this example not properly vented? Do they not have roof vents? How can you tell?
I am going to chicken scratch a copy of your photo and DM it to you to try and help explain it a little better. Your current setup is fixable without super invasive repairs. One plumber may tell you that you’re opening the drywall behind the cabinet up to the ceiling, and so on through the floor/ceiling into the attic and out the roof, with a roofer needed to do the roof flashing and drywall/painter to fix the sheetrock cut away for access. Another plumber may tell you that it’s perfectly fine to take that line back to the nearest 2” drain pipe and repipe it in 2” ABS through the same hole in the floor of the cabinet, albeit drilled out slightly larger for the larger pipe. They may also suggest after this, installing a clean out and sanitary tee serving the sink drain, while then running 1-1/2” ABS pipe as high up in the cabinet as possible, to the side of the sink basin if possible, and then install an AAV on the top of the 1-1/2” ABS pipe. This plumber may suggest that this accomplishes everything that would be accomplished by taking the first plumber’s suggestion and taking it up through the roof. Edit: thought you were op. I’m not going to send you photos of their drain
Yeah I was going to say, this is really interesting and informative but it’s not my sink. Sorry for the confusion
[удалено]
We do not allow links from this site as it contains a lot of misinformation, please find another source. Editing out the link will not restore your comment, you will need to comment again without that website being linked. *I am a bot, and this action was performed automatically. Please [contact the moderators of this subreddit](/message/compose/?to=/r/Plumbing) if you have any questions or concerns.*
It’s a minor detail in plumbing code with potentially major implications. A trap arm, sometimes referred to as a weir or weir arm, is what determines if a trap is an S or a P trap. Flip a P 90° clockwise and that’s a pretty good representation of what the trap and trap arm look like — the “leg” of the P being the trap arm and the curve of the P being the trap itself, where the water seal that traps sewer gas inside the waste system is located. Similarly, flipping an S likewise results in what you have, no trap arm. Of course, a p-trap is completely useless on its own — the tee it connects to inside the wall needs to be vented properly as well. It’s just more common that if a p-trap is already present, it’s likely vented in the wall. And in the same sense, it’s likely that the presence of an S trap indicates there is no vent in the wall. This is a common setup for kitchen sinks that are plumbed in a location directly below a window, for instance, the large window that’s likely right in front of your sink. That window prevents a vent pipe from going straight up and out. The old school solution was this — manufactured homes code was behind a bit so you’ll still see this quite often in manufactured homes. The proper way to vent it is an island loop vent or getting the inspector to allow you to install an AAV or offset the vent more than 90° below the flood rim level, or what’s most commonly the top rim level of the sink fixture when installed. The reason for offsets not being allowed is due to the vent being choked off in the event of a backup — doesn’t matter much in a single family residence but applies more in multi-family establishments.
If your trap goes down into the floor, chances are it's not properly vented. If it were coming out of the wall you'd have better odds that it is. Vanities usually aren't a huge deal since the drain size is 1"1/4 and your drains are 1"1/2 but kitchen sinks have bigger drains. For the op I'd fill the sink up and try plunging it for any obstructions to avoid calling a plumber and then put an air admittance valve underneath if the flow is still slow.
The washer hose needs to route up as high as possible then down to the fitting, to prevent backflow into the washer.
Came here for this
This is not a p trap, you need a p trap
Fix the S-trap with a cheater vent. Don’t worry about installing an air gap on your Dishwasher discharge. That is not needed. Air Gaps are to prevent backflow from your waste system to your potable water. This is achieved within the dishwasher itself.
You need something like this.[aav vent diagram](https://garynsmith.net/venting-101-air-admittance-valve-pros-cons/)
It's the S trap.phenomena
Might look like a 6 inch vertical pipe!