Replace a Bathroom Faucet and That Corroded Pop-Up Drain
A new faucet is the cheapest visible upgrade in a bathroom, and the drain under it is usually the thing that has actually failed. Do both in one afternoon with two wrenches and a bucket.
Bathroom faucets fail in slow motion: the finish pits, the aerator clogs, the handle gets stiff, and under the sink the pop-up drain grows a green crust where the tailpiece meets the flange. Swapping both is a genuine beginner project because everything sits above a shutoff valve and every connection is meant to be undone with hand tools. The only hard part is the last 20 minutes with the old fixture, when you are lying on your back under a cabinet fighting a corroded nut.
Match the holes before you shop
Look at the sink from above. One hole means a single-hole faucet. Three holes 4 inches apart center to center means a centerset; 8 inches apart means a widespread. A single-hole faucet with an escutcheon plate can cover a 4-inch centerset arrangement, which is how most people modernize a builder-grade sink. Check that the new drain is the standard 1-1/4 inch and confirm whether the faucet includes one; most mid-range models do.
Shut off, drain, and clear the trap
Close both angle stops under the sink and open the faucet to bleed pressure. If a stop will not fully close, this is the moment to replace it with the house water off, because a weeping valve ruins the rest of the day. Put a bucket under the P-trap, loosen the two slip nuts by hand or with channel-locks, and set the trap aside. Now you can see the whole underside of the drain.
Free the old faucet from below
Disconnect the supply lines at the stops, then at the faucet if they will come. The mounting nuts are up behind the basin where no normal wrench fits; this is what a basin wrench is for. Hook its jaw on the nut, let the spring-loaded head grab, and lever the long handle. If a nut is seized, hit it with penetrating oil, wait ten minutes, and try again. As a last resort, a small hacksaw blade through the plastic nut takes two minutes and saves an hour of swearing.
Remove the corroded pop-up drain
Unscrew the pivot rod nut at the back of the tailpiece and pull the rod out, then loosen the large mounting nut under the sink. Push the flange up from below and lift it out of the basin; if the putty has turned to concrete, twist with pliers on the flange from above. Scrape the old putty ring off the porcelain with a plastic scraper and wipe the area with alcohol until it is bare and dry.
Set the new drain first
Roll a rope of plumber’s putty the thickness of a pencil and press it under the new flange (use silicone instead if the sink is stone or the instructions say so). Drop the flange into the hole, then from below slide on the rubber gasket, friction washer, and mounting nut, and tighten while holding the flange straight so the pivot rod opening points at the back. Snug, not heroic; overtightening cracks porcelain. Wipe the putty squeeze-out from above.
Mount the faucet and connect the supplies
Set the faucet with its gasket or a bead of silicone, hand-tighten the mounting hardware from below, check it is square to the wall, then snug with the basin wrench. Attach the new braided supply lines to the faucet shanks first, then to the stops. Hand-tighten and add a quarter turn with a wrench. Never reuse old supply lines; a $6 hose is cheaper than a ceiling.
Reconnect the trap and test slowly
Slide the P-trap back over the new tailpiece, using new washers if the old ones are brittle. Pull the faucet aerator, open the stops slowly, and run hot and cold for a minute to flush debris. Reinstall the aerator, fill the basin, and release the pop-up while watching every joint with a dry paper towel. A damp towel anywhere means a quarter turn more on that nut.
Old chrome-plated brass supply tubes and compression stops can shear when you wrench on them, and a snapped stop means a house-water-off emergency. Support the stop with a second wrench while loosening the nut, and if the valve body is green with corrosion, plan on replacing it as part of the job.
Everything in a faucet swap is designed to come apart by hand, except the one nut that isn’t.
Keep it looking new
Wipe the finish dry after use for the first month so mineral spots never build up, and pull the aerator twice a year to rinse grit out of the screen. The pop-up rod will need a small adjustment at the clevis strap once the seals settle. Beyond that, a quality faucet will outlast the vanity it sits on, and now you know how to take it with you.
Keep the momentum going
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