Hi,

We recently installed a new sink/vanity in our bathroom. Initially after we installed the new vanity, the water was slow to drain out of the sink. For some reason, it drained fine after we flushed the toilet (or at least that is what I think fixed it). But then a few weeks later it started to drain slowly again. Do you think we have a venting issue? The tub and toilet in the same bathroom work okay.

Also, there is no overflow hole in our new sink, could that be the problem?

Thanks for your help!

The no overflow could be the problem but it could also be affected by the drain being partially stopped up. Is the lavatory on the same wall as the commode? If so you should be able to go down the lavatory drain with a hand held 1/4 inch snake in a drum. You only would have to go about three feet if the stoppage is in the lavatory arm.

Thanks for your reply! Yes, they are on the same wall. I just don't think its stopped up because we never had an issue until we installed the new sink and nothing has gone down but water. Please see the attached pictures; we had to extend the pipe (you can see the new PVC in the left view) because the new sink was not as deep as the old sink; do you think that is the issue?

Did not get the pictures

Here are the attached files. Hopefully it works this time.

The missing overflow is not the cause of your slow drain. I do suspect your vent stack is partially clogged which would require rodding from the roof, if that is safe. Can you get to your vent stack safely this time of the year, if so drag up a garden hose. Where do you live, that S trap is illegal in the US. You could have avioded the S trap by using a long tail piece. Back to you.

If the vent stack is partially blocked, it is possible for the sink to drain slow, but the tub and toilet work okay?

Thanks for your help!

Probably not since they are all on the same vent. Remove the trap and rod with a drum auger into the lateral line sticking out of the wall. Try to get 10' in with plenty of turning on the drum. How long has this been an S trap?

Okay, thanks! Its been like that since we bought the house 4 years ago; surprised that it wasn't caught by our inspector. We are going to work on it this weekend, change the S trap, etc. I will post once we get it working again!

We finally got our drain to work normally. After having a professional come out to look at it, he determined it was our pop-up drain. Apparently, the drain plug wasn't sitting high enough in the open position, so it was an easy fix after all.

I was to late, sorry. I just found this post and my first thought(with new sink) was the p.o. asssembly. Had I been here sooner, I would have suggested pulling the stopper, and see how it drained then.

Glad you got it fixed. I would still look at redoing the trap set up, so you don't have an s trap. Use a long tailpiece(extension tube) as Ballengerb1 suggested.

However, at this point this would require cutting into the wall and cutting and replacing a fitting, so, as long as everything is working fine now, I wouldn't worry about it, unless you start to get sewer gas smell in the future.