IKEA's instructions are in(famous), with their illustrated diagrams, lack of words, and the oddly bulbous "IKEA man." For the most part, with some head scratching, you can figure them out. But, as we discovered in our recent bathroom makeover, when it comes to installing a sink, the Swedish retailer left out one major detail, which is essential to the job. Read this before you shut your water off and get to work.
If you are a plumbing expert, and know everything there is to know, then you might not find this post helpful. You might roll your eyes at the rest of my amateur ignorance. But if this is your first whack at installing a new sink, and you are going the IKEA route, then read on.
There are two parts that you'll need to connect under the sink: 1) the faucet supply lines, which are the smaller twin pipes to the right. (Usually faucet supply lines come out of the wall as well, but in this bathroom, they came up through the floor); and 2) the main drain pipe (the thick one sticking out of the pegboard wall on the left).
While the faucet connection is very straightforward (more on that below), you will need an additional part to connect the sink to the main drain pipe, which is not mentioned in the IKEA instructional diagram. The main drain pipe in the wall is 1.5" while the sink pipe measures 1.25", so you need an adapter to fit the two together.
I ran out and found one at my local True Value hardware store, but they carry them at Home Depot as well, if you know what to ask for: a drain trap connector. The one I used was made of thick rubber with steel bands, which you use to tighten around the pipes. There are probably other types; you'll have to figure out which works best for your drain configuration.
*** Editor's note: After reading a good comments down below, I'm adding in that these rubber adapters might not be considered up to code in your area. Check to make sure, before you install one. Or, to be on the safe side, use the hard plumbing version of an adapter instead!
Here's the step-by-step instructions: