How to tighten / connect these pipes under the bathroom sink?

Question

I just realized the pipes below the bathroom sink are not glued or tightened in anyway.

1. It fits into the wall outlet but I can turn it easily
2. The light part is bigger than the dark pipe

What is the correct way to connect / tighten these 2?

Thanks,

Answer 1

You should be able to turn both of them clockwise to tighten. They both should have a tapered hard rubber/plastic or black rubber gasket that is squeezed and tightens around the inner pipe (the male part of the fitting) to create a water tight seal.

Comment About Tightening

What I do it to tighten them up as much as I can with my hands. It's almost impossible to overtighten with hands given the awkward position of the nuts. Then I run some water and check for leaks. If any leaks show up, then I come back with a wrench or big pair of pliers and tighten the offending joint a bit, maybe 1/16 of a turn and recheck. Have to be careful because too much force can distort and damage the gasket.

Also, you should get rid of that flex coupling. You should be able to find some combination of rigid pipes and couplings to use there.

Answer 2

As an alternative to SteveSh's answer, the simple solution to the drain tailpipe problem is you probably have 1 1/4" there and the rest of the drain assembly is probably 1 1/2". You could just install a reducing washer at the part that pulls off and call it good (this would be the cheapest solution). No, the flex pipe isn't good, but none of it seems to leaking or problematic (for now).

If you're looking for a better fix, pull the tailpipe from the wall, reduce it to 1 1/4" there, and then re-plumb everything to the sink pipe. Shouldn't be expensive, but you will have to get creative on the drain fittings since they don't line up.