Kitchen Drain Backing up
#1
03-06-22, 07:04 PM
Kitchen Drain Backing up
Evening all....I just replaced the drain lines to a double bowl kitchen sink and disposal. Water backs up into the sinks. I checked all pipes and they seem to be pitched properly. Additionally, I snaked the waste line going into the floor of the cabinet and no obstructions. I plumbed just one sink to see if it still happened and it did, so it seems like the water is not getting above the p trap and backing up. ANy thoughts on how I can fix this?
If it helps for me to add a picture of the drain lines let me know.
Thanks Bud
If it helps for me to add a picture of the drain lines let me know.
Thanks Bud
Top Answer
03-07-22, 04:58 PM
Group Moderator
Well a couple things. I don't know if it's the camera angle or what, but the line going horizontally out of the disposal only needs to be pitched at 1/4" per foot. More is not better! So you might need to cut the tailpiece coming down out of the right sink shorter so that the pipe coming out of the disposal doesn't run downhill so much.
I would also definitely eliminate the horizontal run and elbow between the slip joint tee and the p trap. Instead, your tailpiece and tee under the sink should go straight down into the p trap. Then the weir coming out of the p trap should be aimed right at your drain. Where the slip joint weir of the p trap ends, you will transition to 1 1/2" schedule 40 pipe with a slip joint adapter on the end.
You also likely should have an AAV under the sink. I don't know that it needs it, but it certainly wouldn't hurt.
Cut right below the 2" coupler, and remove everything above it. Install a new 2" coupler. Then you probably should plumb that AAV vent as high as possible under your countertop, left or right of the sink.
You would install a short amount of vertical pipe into the 2" coupler (length determined later), then a 2" x 2" x 1 1/2" sanitary tee. You want that tee to be positioned so that your trap weir will have the correct 1/4" per ft slope. More slope is not necessarily better. So figure out where the tee needs to be heightwise, and cut the short length of pipe to fit between the 2" coupler and the bottom of the tee. The 1 1/2" side of the tee will be turned to aim right at your trap weir. You would then likely need a short section of 1 1/2" pipe and a 1 1/4" or 1 1/2" SJ adapter to slide your trap weir into. That would complete your drain.
Now on to the AAV. On top of the tee, you will likely want to glue in a street 45 elbow that will head to your AAV in either the left or right back corner of the cabinet.
The AAV needs to be as high as possible. So take your 2" AAV, glue it into a coupler or screw it into a 2" fitting, and hold it up to the bottom of the countertop. Then you will likely need a short amount of pipe right below that to get below the sink bowl... then a 45 elbow, and a section of pipe to connect it to the other 45 street elbow that you glued into the tee.
This sounds like a lot, but I think you will find that it will drain a LOT better, unless you happen to have a clog downstream, or something improper below the cabinets that we can't see.
I would also definitely eliminate the horizontal run and elbow between the slip joint tee and the p trap. Instead, your tailpiece and tee under the sink should go straight down into the p trap. Then the weir coming out of the p trap should be aimed right at your drain. Where the slip joint weir of the p trap ends, you will transition to 1 1/2" schedule 40 pipe with a slip joint adapter on the end.
You also likely should have an AAV under the sink. I don't know that it needs it, but it certainly wouldn't hurt.
Cut right below the 2" coupler, and remove everything above it. Install a new 2" coupler. Then you probably should plumb that AAV vent as high as possible under your countertop, left or right of the sink.
You would install a short amount of vertical pipe into the 2" coupler (length determined later), then a 2" x 2" x 1 1/2" sanitary tee. You want that tee to be positioned so that your trap weir will have the correct 1/4" per ft slope. More slope is not necessarily better. So figure out where the tee needs to be heightwise, and cut the short length of pipe to fit between the 2" coupler and the bottom of the tee. The 1 1/2" side of the tee will be turned to aim right at your trap weir. You would then likely need a short section of 1 1/2" pipe and a 1 1/4" or 1 1/2" SJ adapter to slide your trap weir into. That would complete your drain.
Now on to the AAV. On top of the tee, you will likely want to glue in a street 45 elbow that will head to your AAV in either the left or right back corner of the cabinet.
The AAV needs to be as high as possible. So take your 2" AAV, glue it into a coupler or screw it into a 2" fitting, and hold it up to the bottom of the countertop. Then you will likely need a short amount of pipe right below that to get below the sink bowl... then a 45 elbow, and a section of pipe to connect it to the other 45 street elbow that you glued into the tee.
This sounds like a lot, but I think you will find that it will drain a LOT better, unless you happen to have a clog downstream, or something improper below the cabinets that we can't see.
#4
03-07-22, 10:49 AM
Afternoon all. I changed the drain lines because sometimes the disposal would clog and I would turn on the disposal the water would come out the second bowl. As far as I know, it didn't appear there was any backing up. It was the disposal that was clogged. Additionally, I knew the drain lines were installed wrong. Both bowl drain lines were connected to a T in the middle.
When I was working on this I ran the drain lines from only one bowl directly to the p trap and it backed up in the one bowl. That's what is a head scratcher for me.
Thanks Much
When I was working on this I ran the drain lines from only one bowl directly to the p trap and it backed up in the one bowl. That's what is a head scratcher for me.
Thanks Much
#6
03-07-22, 04:58 PM
Group Moderator
Well a couple things. I don't know if it's the camera angle or what, but the line going horizontally out of the disposal only needs to be pitched at 1/4" per foot. More is not better! So you might need to cut the tailpiece coming down out of the right sink shorter so that the pipe coming out of the disposal doesn't run downhill so much.
I would also definitely eliminate the horizontal run and elbow between the slip joint tee and the p trap. Instead, your tailpiece and tee under the sink should go straight down into the p trap. Then the weir coming out of the p trap should be aimed right at your drain. Where the slip joint weir of the p trap ends, you will transition to 1 1/2" schedule 40 pipe with a slip joint adapter on the end.
You also likely should have an AAV under the sink. I don't know that it needs it, but it certainly wouldn't hurt.
Cut right below the 2" coupler, and remove everything above it. Install a new 2" coupler. Then you probably should plumb that AAV vent as high as possible under your countertop, left or right of the sink.
You would install a short amount of vertical pipe into the 2" coupler (length determined later), then a 2" x 2" x 1 1/2" sanitary tee. You want that tee to be positioned so that your trap weir will have the correct 1/4" per ft slope. More slope is not necessarily better. So figure out where the tee needs to be heightwise, and cut the short length of pipe to fit between the 2" coupler and the bottom of the tee. The 1 1/2" side of the tee will be turned to aim right at your trap weir. You would then likely need a short section of 1 1/2" pipe and a 1 1/4" or 1 1/2" SJ adapter to slide your trap weir into. That would complete your drain.
Now on to the AAV. On top of the tee, you will likely want to glue in a street 45 elbow that will head to your AAV in either the left or right back corner of the cabinet.
The AAV needs to be as high as possible. So take your 2" AAV, glue it into a coupler or screw it into a 2" fitting, and hold it up to the bottom of the countertop. Then you will likely need a short amount of pipe right below that to get below the sink bowl... then a 45 elbow, and a section of pipe to connect it to the other 45 street elbow that you glued into the tee.
This sounds like a lot, but I think you will find that it will drain a LOT better, unless you happen to have a clog downstream, or something improper below the cabinets that we can't see.
I would also definitely eliminate the horizontal run and elbow between the slip joint tee and the p trap. Instead, your tailpiece and tee under the sink should go straight down into the p trap. Then the weir coming out of the p trap should be aimed right at your drain. Where the slip joint weir of the p trap ends, you will transition to 1 1/2" schedule 40 pipe with a slip joint adapter on the end.
You also likely should have an AAV under the sink. I don't know that it needs it, but it certainly wouldn't hurt.
Cut right below the 2" coupler, and remove everything above it. Install a new 2" coupler. Then you probably should plumb that AAV vent as high as possible under your countertop, left or right of the sink.
You would install a short amount of vertical pipe into the 2" coupler (length determined later), then a 2" x 2" x 1 1/2" sanitary tee. You want that tee to be positioned so that your trap weir will have the correct 1/4" per ft slope. More slope is not necessarily better. So figure out where the tee needs to be heightwise, and cut the short length of pipe to fit between the 2" coupler and the bottom of the tee. The 1 1/2" side of the tee will be turned to aim right at your trap weir. You would then likely need a short section of 1 1/2" pipe and a 1 1/4" or 1 1/2" SJ adapter to slide your trap weir into. That would complete your drain.
Now on to the AAV. On top of the tee, you will likely want to glue in a street 45 elbow that will head to your AAV in either the left or right back corner of the cabinet.
The AAV needs to be as high as possible. So take your 2" AAV, glue it into a coupler or screw it into a 2" fitting, and hold it up to the bottom of the countertop. Then you will likely need a short amount of pipe right below that to get below the sink bowl... then a 45 elbow, and a section of pipe to connect it to the other 45 street elbow that you glued into the tee.
This sounds like a lot, but I think you will find that it will drain a LOT better, unless you happen to have a clog downstream, or something improper below the cabinets that we can't see.
Budster17,
Trying2Help
voted this post useful.
