This account will be in reverse order since I had no idea what I was getting into when I first found that my bathroom shutoff valves had been leaking for some time.
Tip 1: The plumbing industry has no clue when it comes to best practices or Lean Manufacturing. For every job there are at least 3 different ways to do things. For this reason you should familiarize yourself with these acronyms - FIP, MIP, ZIP (to search out the closest Home Depot), COMP, ID, OD, PVC, ABS - as well as such esoteric things as sweating pipe, the best tools to cut pipe of various sorts, or whether you need a dielectric union to complete your job. You should also fill up your gas tank because every job takes 3 (count 'em) trips to the hardware store. In the example of last night I was trying to attach both the water lines and the drain to my new vanity so it took 6 trips.
Tip 2: If the drain pipe coming out of the wall is less than 24" from the floor you will need and extender.
Tip 3: If your water inlets are less than 16" from the floor you will need longer supply lines that aren't right in front of your nose at the store (they are packaged differently than the shorter ones). Note that the shorter ones you see in front of your face are probably harder to install because it means the shutoff valve is directly behind the P-trap you just installed.
Tip 4: When you install the new faucet on your new vanity do it before you set the top on the vanity and make sure that the lever for the stopper is facing the back. This is probably only for those who bought a faucet where the neck swivels 360. Otherwise you'll have to take the whole thing apart again to make it so you pull rather than push the handles to turn on the water. It's no use trying to change that around while everything is in place because you'll inevitably strip the threads when trying to hook the supply line back up to the faucet. Did I mention that this connection is behind the sink and really awkward to get to?
So, are you ready to proceed?
Trip 1. I already know that my water shutoff has an angle 1/4 turn compression fitting because when I took the nut off (the one you aren't going to use anyway) it had a brass collar inside. I don't know what size it is but I'll take the nut with me and figure that out at the store. At the store you'll find this nice display where all the supply lines slide onto collars. They are supposedly in order so you can grab 2 from the same place. First the shutoff side of things. I discovered that my nut matches a hose marked 3/8". I grabbed a couple 20" hoses that had plastic fittings at the top so they could be tightened by hand. The next step was the P-trap. I told the 'pro' that I have 1 1/2" ABS coming out of the wall and a standard 1 1/4" drain on the vanity. He told me I needed a 1 1/4" P-trap and an adapter from Aisle 7 at the wall end. I took my P-trap to Aisle 7 where the other 'pro' told me to follow him back to Aisle 5 where he showed me that the 1 1/2" P-trap comes with an extra washer to make the reduction to 1 1/4". Cool!
Trip 2. Now why would they make the inlet for a toilet tank a different size than one for a faucet? The pipe coming out of the wall is the same size so what's the point. So now I grab 2 hoses meant for a faucet but 'pro' #1 tries to tell me that faucets come in either 1/2" or 3/8" so I go to Aisle 4 to confirm what I already know - all new faucets are 1/2". Unfortunately the new hoses don't have the nice plastic ends to tighten them up so it was a pain trying to get my crescent wrench in there to tighten them up. Now I'm ready to set the vanity top in place.
Trip 3. Yup, my shutoff comes out of the wall too low for a 20" hose. Since I'm pissed off at 'pro' #1 at Home Depot I head even further to Lowes for these parts. I add the other 2 hoses to my growing pile of items to be returned from this project.
Trip 4. Now it's time to tackle the drain. I see that the P-trap kit doesn't come with a nut and washer to connect it up to the ABS pipe coming out of the wall. I've swallowed my pride in favor of a shorter trip to Home Depot.
Trip 5. Since the pipe coming from the wall is too low I need an extension to reach from the sink to the P-trap. Now that everything is hooked up I turn on the water supply and see that there are no leaks. Yeah! Turn on the faucet. Oh crap! I installed it backwards so I try to swap it without taking everything apart. One supply line goes on the faucet well but the other one is cross-threaded so everything has to come apart.
I hate plumbing!
Trip 6. A short trip to the liquor cabinet.
