I've been struggling for a few days trying to unclog a bathroom sink that is extremely slow to drain. I tried the following:

  • Removed and cleaned P trap
  • Snake: Cheapo ($30) 25ft 1/4" drum auger with drill attachment. I hit resistance at varying points along the way which I broke through with a few trials until I had the entire snake fed through. I did it a few more times because I still felt areas of resistance, but eventually the snake became kinked and it became useless.
  • Baking soda/vinegar
  • Plunging: This brought up a lot of nasty black biofilm, but since using the shop vac I don't get much of this anymore.
  • 6 HP shop vac in both directions (suck and blow). When in blow mode, it pushes the water through just fine, but when I turn the water back on the clog remains. It does take about 20 seconds of running water until it backs up into the sink, so that tells me the clog is probably far down.

I'm not sure what else I can do other than call a plumber. I'd rather not use harsh chemicals. Any ideas?

  • 1
    At 25' in your resistance is probably bends more than clogs Since you did not clear the problem. Are any of the other drains in the bathroom slow? Toilet, bathtub? The sink vent may be plugged or possibly not there at all causing the slow drain if other fixtures drain normally. I have seen that in the past. When you suck or blow with the vacuum the air is probably being pulled through a vent even in another area of the house.
    – Ed Beal
    Sep 20 '17 at 13:57
  • I do need to plunge or shop vac the tub drain every 6-8 weeks to keep it moving well, but when i do it drains perfect. Toilet is fine. I wound up calling a plumber, and all he did was snake a few times (unsuccessful) and then he poured chemicals down the drain and that is what opened it up. It was a pretty terrible odor.
    – JCB
    Sep 22 '17 at 15:02
  • Caustic soda, if you can get it to the right place, can be very effective. But be sure to read and heed the warnings. It's also possible the slope on the pipe is wrong, and there are some rubbish undersized traps. Does it initially drain well then slow down, or is it slow from the start?
    – Chris H
    Jan 4 '18 at 13:51
  • Have you checked your vents to see if it is an airlock problem ?
    – Alaska Man
    Sep 17 '18 at 17:57

I would go rent a snake. Plumber will do the same by using a snake but the charge to rent and doing it your self will be cheaper.

  • Is there a clean-out opening further along? Apr 19 '17 at 12:02
  • I'm not sure if there is a clean out opening futher along. What does that look like?
    – JCB
    Apr 19 '17 at 23:18

A garden hose works for me; I hook it to the tub spout and turn on the water. Cost is about zero so worth a try.

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