Replacing a laundry tub can be surprisingly simple because most tubs connect to standard supply tubing and drain pipes. Laundry tubs typically are freestanding, so making the connections is easier than if you had to hook them up inside a sink cabinet. To make the process as simple as possible, measure the drain on your existing laundry tub, and buy a replacement that uses the same size. Standard bathroom faucets for 4-inch hole spacing work on most laundry tubs.
Out With the Old
Locate and shut off the valves on the water lines that connect to your laundry tub. Turn the handle clockwise on each valve until the water is off.
Open the hot and cold water knobs on the tub's faucet to confirm that both the hot and cold lines are turned off. Allow as much water as possible to drain from the lines.
Place a bucket beneath the tub. Use tongue-and-groove pliers or a wrench to loosen and disconnect the nut holding the hot water line to the faucet. Repeat the process for the nut on the cold water line. Catch the residual water from the lines in the bucket.
Place the bucket below the drain pipe that extends from the bottom of the sink. Loosen and remove the slip nuts on the P-trap connecting the tub drain to the home's drain line, using the pliers. Remove the P-trap and dump its water into the bucket.
Remove the laundry tub, being careful not to jostle or damage the water and drain lines that remain behind. If the tub does not lift easily, make sure that it is not screwed or bolted to the floor.
Remove the mounting nuts on the underside of the tub faucet, and lift the faucet from the top of the tub.
In With the New
Locate the perforated or marked "knockout" holes on the new tub for the faucet stubouts and the drain fitting. If there are no knockout locations, mark the holes for the faucet and drain as directed by the manufacturer. Cut out the knockouts with a utility knife, or drill the holes with a hole saw. You'll need one size of hole saw for the sink stubouts and another size for the drain hole, as applicable.
Turn the laundry tub upside down. Connect the legs and base. If the legs need to be hammered into place, put a piece of wood or other scrap material between the leg and hammer to avoid causing damage.
Stand the tub up on its legs. Install the new faucet following the manufacturer's directions. Depending on the faucet design, you may need to apply silicone caulk to seal the faucet base to the sink. Secure the faucet with the provided retaining nuts. Alternatively, install the old faucet onto the new tub.
Position the tub in its final location and confirm that the drain hole is aligned with the drain piping. Anchor the tub to the wall with stainless steel wood screws, driving the screws into wall studs. Note: Not all tubs require anchoring, but it's a good idea to secure lightweight tubs to prevent damage to the drain or supply lines caused by accidental shifting of the tub.
Connect the water supply lines to the tub faucet, and tighten the nuts with the pliers or a wrench. Do not overtighten, especially if your faucet's lines are plastic.
Install the new drain assembly into the tub as directed by the manufacturer. Connect the P-trap to the tub drain and the home's drain line. If necessary, trim the tub's drain pipe with hacksaw to fit properly into the P-trap. Sand off any pieces or clinging plastic around the cut, using fine-grit sandpaper. Secure the P-trap at both ends with the original slip nuts, tightening the nuts with the pliers. Reopen the valves on the water lines and run the faucet to check the installation.