We just installed a new vanity which is higher than the old. The drain piece is not long enough to go into the P trap. Also, we are missing the nut to connect it to the P trap (we think we threw it out with the old sink). Big box stores have advised us to completely replace the P trap (and we bought the parts) but unsure why? Don't they make extensions for this purpose and can we not buy a replacement nut?

Hi Renovating:

Exactly! In fact, messing with the old trap could make a bigger issue for you! A rule of thumb is to not mess with old plumbing unless you need too... could end up in the wall with a real big mess!

I think you should buy a compression extension tailpiece and a new nut and washer and you should be all set here. Just like you thought! :)

Mark

Big boxes are great places to find just about everything... except qualified advice.