Quick Answer:
If water comes from both the showerhead and the tub spout when you run the shower, the diverter (the part that directs water to the showerhead) is the most likely cause. A simple test is to remove the showerhead briefly and watch the flows: if the spout still runs while the showerhead gets more flow, the diverter is likely failing and needs cleaning or replacement.
Why This Happens
Most tubs and showers use a diverter to route water to either the tub spout or the showerhead. Common causes for water running from both outlets at once:
- Worn or stuck diverter: seals or moving parts inside the diverter can wear or collect mineral deposits so they do not fully close.
- Valve or cartridge issues: some systems use an internal valve or cartridge to divert flow; if that part leaks internally both outlets can get flow.
- Incorrect or mismatched tub spout: a spout with a damaged or missing diverter will let water flow out even when the valve is set to shower.
- Problems after repairs: if the faucet, spout, or cartridge was recently replaced and the spare parts don’t fit or were installed wrong, you may see both outlets flowing. See Tub spout leaking after faucet replacement for that type of situation.
If you have a situation where water only appears when the diverter is pulled, that’s a specific symptom to check: Leak only when diverter pulled.
Step-by-Step What to Do
1. Observe and confirm the problem
- Turn on the shower and note if water comes from both the showerhead and the tub spout at the same time.
- Try different hot/cold mixes to see if it changes the behavior (some valves behave differently under different pressures).
2. Remove the showerhead briefly and watch the flows
- Unscrew or pull off the showerhead (have a towel or bucket ready for drips).
- Turn the shower on briefly and watch both outlets. Remove the showerhead briefly and observe whether flow increases there while the spout still runs; heavy spout flow in shower mode points to diverter failure.
3. Check the tub spout diverter
- If your spout has a pull-up or push-down diverter, inspect it for mineral deposits, grit, or broken parts.
- Try operating the diverter several times to free any grit, then test again.
4. Clean or replace simple parts
- Clean mineral buildup from the spout and showerhead openings. Reattach and test.
- If the spout’s diverter is damaged, replacing the tub spout is often an inexpensive fix.
5. Know when the valve needs work
- If the diverter is inside the mixing valve (cartridge-style units), the cartridge or internal diverter may need repair or replacement. That is more involved and can require shutting off water and removing trim.
- If you’re not comfortable with that disassembly, call a professional.
6. Test and watch for leaks
- After any cleaning or replacement, run the shower and check that the spout stays closed in shower mode and that pressure is acceptable.
- Look for drips around the valve trim or under the tub that could indicate a deeper leak.
What Not to Do
- Don’t ignore water running from both outlets—this wastes water and reduces shower pressure; if it’s persistent, a plumber is appropriate.
- Don’t force or hammer the diverter parts; that can break components or damage the spout.
- Don’t use glues, sealants or random fillers to “stop” the flow; these can make later repairs harder and create unsafe conditions.
- Don’t remove an internal valve cartridge unless you know how to shut off the water and reassemble the trim correctly.
When to Call a Professional
- If the diverter is inside the valve or the cartridge needs replacing — this usually requires more time, parts, and skill than simple spout replacement.
- If cleaning and a spout replacement don’t fix the problem, or if you see water leaking behind the wall, call a plumber.
- If you recently had faucet or cartridge work and now have persistent spout flow, consider professional help — see Tub spout leaking after faucet replacement for similar cases.
Safety Notes
- Turn off the water supply to the tub before doing any major disassembly. If you can’t shut off the local supply, shut off the main water to the house.
- Be careful of hot water when testing; brief tests are safer than long runs when temperature is high.
- Use the right tools and protect finishes. If you’re unsure, stop and call a pro to avoid damaging tile, trim, or plumbing parts.
Common Homeowner Questions
- Why does my tub spout still run when the shower is on? A worn or stuck diverter or an internal valve leak is the usual cause.
- Can I fix this myself? You can clean or replace a spout diverter yourself, but internal valve or cartridge repairs are best left to a plumber unless you have experience.
- Will this damage my plumbing if I leave it? It wastes water and can reduce pressure; persistent internal leaks can lead to larger problems and should be addressed.
For more related articles, see the Tub Spout Leaks When Shower Is On hub.