I have a kitchen sink that is recently backing up when I run the sink. I ran the garbage disposal thinking this would solve the problem but once I turn off water (lots) bubbled up into the sink. If I just leave it, the water does drain out. And in fact I thought the problem was fixed because I rapidly poured a whole kettle of boiling water down the sink and it all quickly flowed down the drain. I reheated kettle and repeated 5 times. We even ran the dishwasher over night and as far as I can tell, it got the dishes clean and didn't back up (no water in dishwasher). But when I turned on the sink and the garbage disposal in the morning, same problem. Water comes gurgling up.

I'd like to know

  1. Why do things seem worse when using garbage disposal?
  2. What's going on and how do I fix it?

I did see this article: Water backs up in adjacent sink only when garbage disposal is used

and maybe that addresses my problem? But note that I just have a single drain not a double one.

Thanks! Dave

Update. Photo shows plumbing under sink. Notice I was able to undo bottom connection of trap but NOT top connection. I unscrewed the fastener. Should it just pull down now? For the life of me, I can't budge it. AND I may have caused leak from pulling/twisting. Seemed like water was coming out when I ran garbage disposal right now metal fattener on outside of disposal (connector to tube) Adding photos as requested: UnderSink

  • Thank you everyone. I figured out the problem and how to call a drain service! I took trap off and examined it and garbage disposal. All clear. Problem was blockage 15' down line. That's why it would slowly drain over time. I tried to snake it myself and changed a slow drain problem to a "no drain" problem. Plumber brought power snake and fixed it.
    – Dave
    Commented Apr 17, 2017 at 20:43

2 Answers 2


First of all, I don't recommend using boiling water to clear things in most cases. If you have grease build-up, the boiling water may melt a bit and move it a little further away, but it will then solidify further down the line as it cools. If it's not grease, the boiling water isn't likely to do much that cold water wouldn't do as well. (And if this is your problem, try what you can to limit grease entering the drain in the first place).

Sounds like you have a single basin sink with the disposal underneath. A picture of the plumbing would help.

First thing I would do on a standard sink is pull the trap. Normally it should be there in a way that you unscrew two connectors and it comes free (have a bucket and some towels ready.

Normally there should be water in the trap, but not much in the line away. Examine the trap and see if it's got a blockage. Look in the line away and see if it's clear. If there's a blockage, clear it with a snake.

If it's a simple blockage, I'm confused why the disposal would make it worse.

  • BowlOfRed, You mentioned two connectors for trap. You can see in my photo that I disconnected bottom one and it came away freely. Is there a trick with the top one? I unscrewed fastener and though I'd be able to just pull down, but no luck. Also notice I may have water now coming out near metal fasten between disposal and pipe. Is this adjustable? Thank.
    – Dave
    Commented Apr 8, 2017 at 13:08
  • @Dave, yes normally you should be able to simply pull down on that straight section of pipe to remove it (since you loosened the SJ (slip-joint) nut), but there's always a chance someone did something screwy and glued it. You can remove the metal plate to get that assembly off if you need to, note there is a special rubber gasket behind that plate (special and specific to your disposer brand- I.S.E.), if it leaks now (or later) you made need to purchase a new one. It may seal up fine when you reassemble things. Commented Apr 8, 2017 at 15:03
  • Exactly. I would take the pipes on both sides of where the upper ring was and gently rock them to see if it's just stuck together. Also at this point if you have a snake you can probe either the trap or the line and see if there's a blockage.
    – BowlOfRed
    Commented Apr 8, 2017 at 15:36

Sounds like your trap has something caught in it.

If it gets worse when you run the garbage disposal it would be because it is trying to push more down there.

Sounds like Drano would be a good first step. And if that doesn't work then pull off your trap and take a look.

  • Thanks for the answer. I updated the question with picture. Basically, I'm having a hard time getting trap off. Is there a trick?
    – Dave
    Commented Apr 8, 2017 at 13:06
  • That picture helps a lot. For actually removing the trap, it looks like you loosened the top part of the trap so it should pull free. Maybe rotate it a bit back and forth. And pray no glue got in there. If it won't come loose I would put a bucket under the open part, run some water in the sink and see if it is free-flowing to the back of the trap. If it is clear to that point then the problem is further down inside the plumbing somewhere, which means running a longer snake in towards the back.
    – SDsolar
    Commented Apr 8, 2017 at 19:42

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.