Quick Answer:
If the tub spout only leaks when you pull the diverter, the problem is usually the diverter seal or the spout itself, not the main valve. Test the diverter’s movement for grit or rough travel, then remove and inspect the spout—clean or replace the seal or the spout if worn. Don’t force the diverter; if the leak continues or you can’t remove the spout, call a plumber.
Why This Happens
The diverter redirects water from the spout up to the shower. When the diverter is not engaged the normal spout path seals or sits under different pressure, so you see no leak. Pulling the diverter changes flow and pressure inside the spout and exposes any worn seal, damaged diverter gate, or gaps in the spout body. Mineral grit or a warped internal seal are common causes.
If the problem started after work on the faucet or spout, see Tub spout leaking after faucet replacement for related scenarios to check.
Step-by-Step What to Do
1. Prepare and test the diverter travel
- Turn the taps off and run the shower briefly to relieve pressure. If you prefer, shut off the water supply to the tub at the local shutoff or main.
- Pull and push the diverter several times. Pay attention to how it feels: smooth travel is normal; gritty, rough, or sticky movement usually means mineral deposits or debris are preventing a full seal.
- If the diverter feels gritty, try cycling it more gently a few times to dislodge grit. Don’t force it hard.
2. Identify the spout type
- Most spouts are either slip-on (held by a set screw under the spout) or threaded (unscrews from the pipe). Knowing the type tells you how to remove it safely.
- Look under the spout for a small screw (slip-on) or twist the spout counterclockwise by hand (threaded). Protect the finish with a cloth if you use pliers for extra grip.
3. Remove and inspect the spout
- Remove the spout per its type and inspect the diverter mechanism and the inside of the spout for mineral buildup, broken parts, or a missing/brittle rubber seal.
- Clean mineral deposits with a soft brush and a vinegar soak if needed. Replace any torn or collapsed rubber seals.
4. Replace the spout or seal if worn
- If the seal or internal diverter part looks worn, replacing the spout is often the simplest fix. Match the spout style (slip-on vs threaded) and length to your pipe.
- After replacement, test by pulling the diverter and watching for leaks. If the leak stops, you’re done.
5. If the leak continues, inspect further or call help
- If replacing the spout and seal doesn’t stop the leak, the diverter inside the valve body may be damaged or the valve trim needs attention. That is a more complex repair.
What Not to Do
- Don’t keep forcing the diverter harder to stop a leak—forcing can break the diverter or strip a set screw.
- Don’t hammer or lever the spout aggressively; that can damage the plumbing behind the wall.
- Don’t ignore a leak that continues after you try a spout replacement; persistent leaks can lead to water damage.
- If it leaks only when pulled and simple cleaning/replacement doesn’t help, a plumber is appropriate rather than repeated DIY attempts.
When to Call a Professional
Call a plumber if:
- You cannot remove the spout without risking damage.
- Cleaning or replacing the spout and seal does not stop the leak.
- You suspect the diverter inside the valve body is broken or you see signs of water behind the wall or on the floor.
- If the problem appeared or worsened after other work, consider professional help—especially for complex trim or valve repairs: Leak worsened after plumbing repair.
Safety Notes
- Shut off water or relieve pressure before removing a spout to avoid an unexpected spray.
- Be careful of hot water when testing the diverter to avoid scalding.
- Use hand tools with protectors (cloth) to avoid scratching finishes and to get a safe grip.
- If you’re unsure how to reinstall parts or if pipes are corroded, stop and call a professional to avoid making the problem worse.
Common Homeowner Questions
- Q: Can I fix it myself? — A: Often yes for worn seals or mineral buildup; replace the spout if the seal is gone. Stop and call a plumber if removal is difficult or the valve internals are suspect.
- Q: How much will a spout replacement cost? — A: Parts are usually inexpensive; expect higher cost if a plumber is needed for valve work.
- Q: Will cleaning remove the leak? — A: Cleaning can stop leaks caused by grit or mineral deposits, but torn seals or cracked spouts require replacement.
For more related articles, see the Tub Spout Leaks When Shower Is On hub.