how do I replace a drain in my bathroom sink?

Answer 1

You will need a pipe wrench big enough to fit onto the nut of each section of the drain. Then look under there and see that there is a piece of pipe (called the tail piece and maybe 4-6 inches long) that goes straight down from the drain and ends up inside the u-shaped piece of drain pipe. Where the two comes together you will see a big nut holding it there. Hold the U-shaped piece with one hand and put a wrench on that nut and twist it counter clock wise. When it loosens turn it the rest of the way by hand and then just slide it up to be sure it is loose. Now look up to where that straight piece comes through the bowl of the sink. You will see another nut that is up at that top. Put a wrench on that nut and twist it counter clock wise. When it loosens turn it the rest of the way by hand and drop it down toward the bottom. Now use a wrench to grab that loose piece of straight pipe and twist it so that it is loose enough to grab and push up out of the sink's top.

The only other complication would be if there is a handle or knob that you pull to make the drain plug pop up and down. if there is look under the sink for where a screw attaches it to a rod sticking out of the drain and loosen that screw.

Take that piece to a place like Home Depot. Tell them you want a replacement for that exact thing you brought in. Also get some plumbers putty and some Teflon tape. Also ask them if there is anything else you need to know for that exact drain.

Now bring the new piece home and take some plumbers putty, roll it into a quarter inch thick snake shape, and put it under the bottom edge of the drain so water can't leak from there. Put the drain piece in and slip the nut up onto the piece from underneath. Now wiggle the end of the tailpiece into the u shaped drain pipe. Press the drain down and tighten the nut first by hand and then with the wrench so that the drainpipe is getting tightly into place and the putty is squishing out uniformly around it. Tighten up that nut and wipe away any putty that shows on the top of the drain. Now go back underneath and tighten the nut that is on the u shaped drain piece. Reconnect that drain popup handle as it was before.
Turn on the water and make sure it is not dripping. If it drips aound the top of the u shaped drain pipe take off the nut again and wrap a piece of teflon tape over the threads before you tighten the nut again. [If you don't need the Teflon tape bring the unopened tape back to Home Depot for a refund.]

Answer 2

You will need to buy a variety of parts. A sink trap (U shaped) plus any parts to connect to drain. Make sure you get the right size for sink and outlet pipe. Plastic or copper will depend on age of house.