How to Replace a Deck-Mount Garden Tub Faucet

The first and most critical step is to prevent water damage. Locate the main water shutoff valve for your house and turn it clockwise until it is fully closed. If your tub has dedicated shutoff valves (often found inside the access panel), you can close those instead. Once the water is off, open the hot and cold handles of the tub faucet to drain any remaining water from the lines into the tub. Place a bucket and rags inside the access panel area to catch any residual drips during disconnection.

Locate the access panel on the wall or framing surrounding the tub. These panels provide access to the plumbing. They may be held in place by screws, clips, or simply pressure-fit. Use a screwdriver if necessary to remove the screws and carefully take off the panel. Place the panel and any screws aside in a safe place. Use a flashlight or headlamp to illuminate the entire area underneath the faucet to inspect the connections you will be working on.

With the bucket positioned underneath, use a basin wrench or an adjustable wrench to disconnect the hot and cold water supply lines from the faucet's valve bodies. The connection nuts turn counter-clockwise to loosen. If the nuts are corroded or stuck, apply a small amount of penetrating oil and wait 10-15 minutes before trying again. It's crucial to use a second wrench or pliers to hold the faucet valve body steady to prevent it from twisting and damaging the pipe.

The most difficult part of the removal process is typically unscrewing the large mounting nuts that hold the faucet handles and spout to the underside of the tub deck. Use the basin wrench to grip these nuts and turn them counter-clockwise. This will require patience and effort due to the awkward angle and tight space. Once the nuts are removed, the old handle valves and the spout can be lifted straight up and out from the top of the tub deck.

After removing the old faucet, thoroughly clean the top surface of the tub deck around the mounting holes. Use a plastic putty knife to gently scrape away any old plumber's putty or sealant residue. Then, use an all-purpose cleaner and rags to wipe the area clean. A pristine surface is essential for the new faucet to seal correctly and prevent leaks.

Carefully follow the manufacturer's instructions for the new faucet. Typically, you will place the included gasket or apply a bead of plumber's putty around the base of the new spout and handle bodies. Insert them into the holes from the top of the deck. From underneath, slide on any supplied washers and then hand-tighten the new mounting nuts. Use the basin wrench to snug them up, but do not overtighten. The components should be secure and not wiggle.

Now connect the plumbing lines to the new faucet. Start by attaching the hot and cold water supply lines to the corresponding faucet valve shanks. If the supply lines do not have a built-in rubber gasket, wrap the male threads on the valve shanks with Teflon tape three or four times in a clockwise direction. Hand-tighten the nuts, then use an adjustable wrench to give them an additional quarter- to half-turn. Do not overtighten.

This is the moment of truth. Go back to the main shutoff valve and turn it on SLOWLY. This prevents a sudden surge of pressure (water hammer). Once the valve is fully open, return to the tub. With the access panel still open, use a powerful flashlight and a dry paper towel to meticulously inspect every connection you made: where the supply lines meet the valves, and where the valves and spout meet the tub deck. Check for even the smallest beads of water. Turn the faucet handles on to let water flow, which will pressurize all the connections, and check for leaks again. If a connection drips, turn the water off and tighten it slightly (about 1/8 of a turn) and re-test.