Often, a leaky bathtub faucet can be fixed, but if the diverter will no longer force water up to the shower without leaking, it is time for a replacement. Luckily, new faucet options are vast at local home improvement stores and via the Internet, and the procedure for installation is simple and takes less than an hour.
Tip: Specialty tools are often not needed, but can sometimes make the job easier as well.
Step 1 - Remove the Old Faucet
Check underneath the faucet for a set screw holding it in place, and use a small screwdriver or Allen wrench to loosen it. The faucet should come off easily once the screw is loosen. If no set screw is present, place the wooden handle of a hammer, screwdriver, or other tool that will fit inside the opening of the faucet and firmly turn counterclockwise.
Make sure to use a wooden handle to avoid damage, and only turn until the faucet can be removed by hand. Once you’re able to set this piece aside, the spout nipple will be revealed.
Step 2 - Purchase a New Faucet
With the old faucet in hand, go to the plumbing department of a home improvement store and purchase another one of identical size and style. The stem which supports the faucet is specifically sized, so keeping this consistent can be important. If an identically sized faucet cannot be found, a new spout nipple can be purchased to make something else fit.
The style of the faucet cannot be altered, however. A slip-on faucet (with a set screw) must be replaced by a slip-on faucet. A screw-on faucet, must be replaced by a screw-on faucet.
Step 3 - Attach the Spout Nipple
If a new spout nipple needed to be purchased, or if the new faucet came with one, the old spout needs to be removed at this time. At the base of the spout is a bonnet nut. This will normally be visible, but at times it can be recessed.
Use the pipe or basin wrench to remove this and the stem will come out with it. If the bonnet nut is significantly recessed, you’ll need an internal pipe wrench instead.
Attach the new nipple spout by using Teflon tape around the threads before you place the bonnet nut on the end. Screw the bonnet nut back into place with the new nipple attached.
Step 4 - Attach the Faucet
Apply Teflon tape around the threads on the nipple spout as well and thread the faucet onto the nipple. Attach the faucet one turn past fingertip tight. Do not over-tighten, as it can bend the spout nipple. Be especially careful if the spout nipple is copper.
Spread caulk around the joint where the new faucet meets the wall to seal it into place. This is often not necessary, but can be applied as a precautionary measure.
Finally, switch on the tub/shower fixture so you know for certain that your replacement has been successful.