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After replacing kitchen sink basket strainer and tailpiece, sink backs up when swamped

SquidstroSquidstro Member Posts: 54
My kitchen sink was leaking under the cabinet, so I saw that the leak was probably from the basket strainer or the nuts and washers being too old.

I took it apart and this was the old setup

The nut on the tailpiece - the washer was rotted away. The basket strainer threads were all chewed up. So I decided to get everything replaced from the slip joint nut & washer up (shown by the pic here):

The blue arrow is the new slip joint nut and a new washer of course. Everything from there and up was replaced. Everything after, I left as is.

There are no leaks at all. However, when you operate the sink, it drains perfectly fine and fast until you overwhelm the basket with water for a while, then it backs up and the pool of water drains painfully slow like there's a blockage. Eventually it will fully drain and when there's no pool, then the drain operates just fine as water enters it.

The old setup did not have this problem at all. It drained just fine. This only started after I replaced things. That's why I don't suspect a clog, rather some issue with physics and the way I decided to replace everything.

The tailpiece is this from Home Depot:

The slip joint nut and washer is this from Home Depot:

And the basket strainer, I got from a specialty plumbing store. I Googled it and found it here:

Thanks in advance for your help fellas!


  • JUGHNEJUGHNE Member Posts: 7,212
    Your new tailpiece may be inserted to far into the J bend of the P trap. J bends usually have a stop point that the tailpiece will hit and must be cut to just the right length. Your tail might be buried too far into the bend causing some blockage.
  • SteamheadSteamhead Member Posts: 14,004
    Maybe the baffle inside the tailpiece where the dishwasher hose comes in is more restricted than the old one was?
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  • SquidstroSquidstro Member Posts: 54
    Ok 2 things:
    1. The tail piece is actually barely in the trap. I'd say about 1/2" where the old setup went in over 1"
    2. The baffle in the new tailpiece definitely looks like it borrows more of the pipe diameter than the older one. The new one looks like almost 1/2" of the diameter it borrows where the old one is about 1/4". I may be over exaggerating that, but I do know from visual alone it looks like it borrows more room.
    So if that baffle is the problem, my only hope is to buy a different one other than the cheap home depot Everbilt ones? And if it is the baffle, what happens from a physics standpoint? The water backflows from the trap until it reaches the sink and once that happens it creates a vacuum and water can't move anymore?
  • BobCBobC Member Posts: 5,130
    Does it make any difference if you remove the strainer? I replaced just the basket and strainer last year with a solid brass unit and I notice the draining speed goes way down if it gets swamped with water, if I take the strainer out all is well.

    Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
    Vaporstat with a 12oz cut-out and 4oz cut-in
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  • SquidstroSquidstro Member Posts: 54
    It doesn't BobC. My problem, I forgot to add, is without the strainer. I'm sure it's worse with the strainer in.
  • FredFred Member Posts: 8,442
    Do you have a basement under this house? Did you fiddle with the drain pipe down there at all? Strange as it may seem, I had a similar problem a couple years ago and for the life of me I couldn't figure out what happened. As it turned out, the run of drain pipe that ran a few feet across the basement had a bow in it at about midpoint. When I raised that back up and put a support on it, the problem was solved. I don't know if that bow created an air trap or some sort of suction in the pipe or what but the problem has never returned.
  • SquidstroSquidstro Member Posts: 54
    No basement, but the kitchen sink is on the 2nd floor.

    My problem with that, is that the old setup drained just fine.
  • FredFred Member Posts: 8,442
    Squidstro said:

    No basement, but the kitchen sink is on the 2nd floor.

    My problem with that, is that the old setup drained just fine.

    So did mine. Is the pipe PVC or steel? Mine was PVC and easily bowed, I guess when I pushed on things to get that "just right fit" :) If your's is steel, not likely to happen BUT, if you ran that PVC pipe into the last fitting (where it goes into the wall), you may have just pushed it to far into an elbow that drops down in the wall, blocking that turn to some degree.
  • SquidstroSquidstro Member Posts: 54
    edited June 2016
    Hmm. The house was completed in 1980, so there was no PVC in the house until repairs started to happen. The trap is PVC now, but in the wall and downstream that's all metal. Only local traps and tailpieces were upgraded to PVC over the years.

    That tailpiece I bought is really all Home Depot has. It's plastic (not even PVC). The trap I left is PVC.

    I didn't shove the trap towards the wall (or wiggle it) to cause what your problem was. I just worked with the pipe from the trap up to the sink.
  • SquidstroSquidstro Member Posts: 54
    edited June 2016
    Ok something dawned on me.

    The old setup was nearly 2" longer.

    With the tailpiece extension, the washing machine branch on the old setup is 5" away from the drain. Now it's only 3".

    Here's the old setup:

    Here's the new setup:

    And here's what the branch union looks like inside the old pipe:

    The old pipe, the union takes up about 1/3 of the diameter. I can't show you the new pipe because it's installed, but it's about 1/2 the diameter.

    So the loss of 2" on the new setup comes from the fact that the new basket strainer is about 1" lower than the old one. Then the tailpiece sticks into the trap about 1/2" now where the old setup was about 1.5".

    Because it fit, I didn't want to waste the time building a tailpiece extension for such a small gain. But what are the chances that the washing machine branch is too close to the drain promoting this issue? Makes me wonder why the old setup had that tailpiece extension then the branch tailpiece which was cut to size at the trap fitting. That locates the washing machine branch 5" down and in the middle of the entire tailpiece setup.

    Ok where are my plumbers and fluid mechanics? :)
  • rick in Alaskarick in Alaska Member Posts: 1,107
    Try taking the p-trap off and put a five gallon bucket under the tailpiece. Then try dumping as much water as you can down the drain and see if it makes a difference.
    I am thinking maybe blocked vent line, or possibly typical sink scum blocking the horizontal part of your drainage. Especially because you took it apart you could have possibly stirred up some crud.
    If it still drains slow with the bucket under it, then I would look at the new basket or the dishwasher tailpiece causing a restriction.
    New thought: If you used the tailpiece gasket off of the basket strainer, I have seen some of them that had a wider flange on them that would block part of the basket drain holes. Look down in the basket and make sure the gasket is not interfering with it
  • Tom_133Tom_133 Member Posts: 702
    I am sure you used the new basket strainer gasket between the strainer and the tailpiece. I have seen some that are manufactured wrong and cut down the flow, or perhaps your strainer is super restrictive. I would do as Rick said and put the bucket under the strainer take apart trap and pour a lot of water down and see if thats the problem.
    Montpelier Vt
  • SquidstroSquidstro Member Posts: 54
    All good info guys.

    Here's something that dents a lot of these theories.

    When my dishwasher runs, it can flood the sink also. It will do the same MO. Drain fine for 10 seconds, then back up and flow into a pool in the sink.

    This is without sink water going in the drain.

    So to me that eliminates the basket or gaskets above the T intersection being restrictive and leads more to a problem with the drainage of the trap or the pipe in the wall possibly.

    I just don't understand why the old setup didn't have this problem and the new one does. Although rick in Alaska made the point of sink scum blocking the horizontal part of my drain.

    I do know that pipe hasn't been cleaned in a long time. And between the dishwasher and the kitchen sink drainage, I bet it's very scummy.

    I'd like to add that I recently did a chemical main line clean with this:

    I put that down my slop sink drain about a month ago. It's on the first floor and the closest to the main (per the instructions). House drainage improved after that, but I understand that was below the kitchen sink and wouldn't have cleaned the upstairs pipes, just from my slop sink to the main. But it did help no doubt.

    Then I'd like to add that I used this:

    In this kitchen sink after this job (because I have the same concerns about the trap and the horizontal pipe being clogged or scummy.

    However, I think it only did work in the trap. You could feel it chemically boiling in the trap, but as it got up to the horizontal pipe, it was cool to the touch. So not sure that cleaner did a lot of work on the horizontal pipe. You can only leave it in there for 15 minutes before cold water rinsing it - and like I said, I think it only really worked in the trap.

    Does anyone recommend a chemical cleaner, like the one I used on my main, where you dump it in and leave it alone for 8 hours and let it eat away scum?

    Or do you guys recommend I take the trap off and have a look in that horizontal pipe to be sure it's obviously a problem and perhaps get a real snake cleaning down it?
  • HillyHilly Member Posts: 412
    You have a choked drain line or maybe a plugged off vent. I wouldn't use chemicals, because I don't need to. They work when used as directed but can be dangerous when used wrong. (ie Drano is for slow moving drains only, not plugged drains) I'd be more inclined to rent a mechanical drain cleaning machine from HD if I was you.
    rick in Alaska
  • SquidstroSquidstro Member Posts: 54
    Thanks Hilly.

    The only thing that makes sense is a choked drain line or an obstructed vent.

    I just don't understand how the old setup didn't flood the sink. Something in this new setup promotes it.

    But I do feel like it has to be a choke or air obstruction in that drain line and the more water you send at it, it just slowly backs it's way to the sink and when it gets there, then a vacuum holds the sink full.

    But let's talk physics there. If the drain works fine for 10 seconds, then backs up into the sink, what creates the vacuum where the water drains slow? I mean painfully slow. Like watching paint dry.
  • FredFred Member Posts: 8,442
    I think you may be too focused on the fact that you replaced that tailpiece. It is likely just coincidental that the drain is stopped up at the same time you replaced that section of pipe. The drain is clogged, probably in a horizontal section somewhere. It works fine for 10 seconds because that's how long it takes to get to the blockage. Much greater probability that the drain is clogged than the vent pipe.
  • SquidstroSquidstro Member Posts: 54
    Another thought of why the old setup possibly didn't swamp is because there were leaks which caused this job. So maybe ironically air was getting into the drain to help it flow better?? Does that make any sense?

    Now that it's leak free, the issue is promoted??
  • FredFred Member Posts: 8,442
    No, not likely. the section of pipe you replaced, that had the leaks would have been filled with water, no air.
  • SquidstroSquidstro Member Posts: 54
    Ok thanks.

    I don't own an auger, and I'm told drain cleaning is pretty disgusting and foul smelling.

    I'd also hate to waste 3 figures on a professional to do something that seems like it should be fairly simple.

    What's everyones' recommendation?
  • Tom_133Tom_133 Member Posts: 702
    Did you try plugging the dishwasher tee and plunging the sink? Fill it the sink a few inches with really hot water 130 degrees ( fill it in a bucket from another source) pour it in the sink and plunge it, see if that does it. If its just grime it will work if its really plugged call a pro.
    Montpelier Vt
  • JUGHNEJUGHNE Member Posts: 7,212
    I would first get enough water thru the drain to flush away any chemicals.......also you don't want to mix different chemicals in the drain.....people have actually died from the fumes that can be generated, extremely rare but can happen.

    It looked like you have a removable No Hub rubber coupling after your P-trap. If you loosen the SS clamps that whole trap will come out and you can see into the Tee in the wall.

    Can you see the vent going up thru the roof. If it is plugged with who knows what, that would cause some problems.
    If it is a straight shot, I have hauled a garden hose to the roof and flushed down the vent to clear it. You want some one to monitor the sink for back up when this is done. (put the trap back on before doing this)

    If the water down the vent comes up in the sink then the problem is in the drain portion of the system.
  • SquidstroSquidstro Member Posts: 54
    Is anyone going to believe me when I tell you that the drain stopped swamping on its own?

    The washing machine drain cycle doesn't flood into the sink anymore, and when you run the faucet for a while the drain keeps up.

    All I can think is that the plumbing job added a clog that is now cleared?

    When I removed the old tailpiece and nuts, some of those washers were disintegrated to almost nothing. Maybe one washed into the trap and got stuck in the waistline.
  • ChrisJChrisJ Member Posts: 11,280
    edited June 2016
    Did you drop stuff (crud, gunk etc) into the trap when you took the old strainer and such apart?

    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • SquidstroSquidstro Member Posts: 54
    That's what I'm thinking.

    I don't recall something obvious - but it's possible.
  • ChrisJChrisJ Member Posts: 11,280
    I'd assume that and it's gone now.

    By the way, in the future I'd highly recommend using a Kohler strainer. I used one on my sink and they're unbelievable.

    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
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