I just very proudly finished installing our new second floor bathroom sink drains. Two different vanities, two different walls. I ran the water steadily in both of them for 10 minutes. One works fine. The other backs up about halfway up the bowl, then suddenly quickly drains everything and repeats...back up, quickly drains, backs up, quickly drains. This is a Kohler drop in sink with no overflow and with a push drain.

THe only difference between the two drain installs is that one is about 1-2 inches offcenter so I used a flexible hose attached to the J-bend. It was sold this way for off-center sinks. I used one on both, but the working sink has very, very little offset.

I really hope this isn't a venting issue. Our contractors have turned out to be not-so-good and we've found it easier to pay someone else to fix their mistakes (or fix them ourselves), but I really do'nt want to rip everything out . The non-draining sink is a new install, but on the same wall as the toilet (which didn't move in the remodel). Is there any way to determine if it's correctly vented?

Thanks

speedball1

Please read the posts, "New Vessel Sink without overflow drains slow" yours isn't the only complaint. This is a venting problem OK but it has to do with venting the drain BEFORE the trap. Regular lavatories vent their drains through the overflow. Most vessel sinks do not have one. This sets up a vacume that impedes the flow. They make drains that address this problem, (read the post), but the grid drains have a problem with surface tension at the grid/strainer that again will impede the drain. Umbrella drains seem to be the ones that work the best. Go read! Regards, Tom