If your bath faucet leaks while the shower is running, you’re dealing with a very common plumbing issue. Instead of all the water going up to the showerhead, some of it keeps coming out of the tub spout. While it may not seem urgent, this wastes water, reduces shower pressure, and can increase your utility bills. The good news is that the problem usually comes down to a faulty part that’s easy and inexpensive to replace.
Why the Tub Faucet Leaks During a Shower
When you turn on the shower, a diverter valve redirects water from the tub spout to the showerhead. If that valve or related parts are worn, water can continue to leak out of the tub spout. The most common causes are:
- Worn Diverter Valve: The internal mechanism that redirects water is damaged or clogged.
- Corroded or Cracked Tub Spout: Damage inside the spout prevents a full seal.
- Mineral Buildup: Hard water deposits block the diverter from sealing properly.
- Worn Washers or Seals: Rubber seals that help redirect water can wear out over time.
- Improper Installation: If the spout or diverter wasn’t fitted correctly, leaks can occur.
How to Diagnose the Problem
Here’s how you can narrow down the issue before making repairs:
- Turn on the shower and observe how much water leaks from the tub spout.
- If only a small trickle, the diverter may just need cleaning.
- If a steady stream flows, the diverter valve or tub spout likely needs replacement.
- If the faucet drips even when both shower and tub are off, the problem is with the main faucet cartridge, not the diverter.
Fixes for a Bath Faucet That Leaks During Shower Use
1. Clean the Diverter
Sometimes mineral deposits prevent the diverter from closing fully. Remove the tub spout (if it has a built-in diverter), soak it in vinegar to dissolve buildup, and reinstall.
2. Replace the Diverter Valve
If cleaning doesn’t help, replace the diverter. There are three main types:
- Spout Diverter: Located inside the tub spout; easiest to replace by swapping the spout.
- Two-Handle Diverter: A separate handle between hot and cold knobs; requires valve replacement.
- Single-Handle Diverter: Built into the faucet cartridge; replace the cartridge.
3. Replace the Tub Spout
If your spout has a built-in diverter that’s worn out, replacing the entire spout is the simplest fix. Make sure to buy the correct type (slip-on vs. threaded connection).
4. Replace Washers and Seals
If accessible, inspect rubber washers or O-rings in the diverter assembly. Replacing them can restore proper function.
Tools You’ll Need
- Adjustable wrench
- Allen wrench (for set screws)
- Replacement tub spout or diverter valve
- Plumber’s tape
- White vinegar (for cleaning mineral deposits)
- Silicone grease (for lubricating new parts)
Cost of Repairs
- Replacement tub spout with diverter: ₦8,000–₦25,000 ($20–$50 internationally).
- Diverter valve replacement: ₦15,000–₦40,000 ($40–$100 internationally).
- Faucet cartridge replacement: ₦20,000–₦60,000 ($60–$150 internationally).
- Professional plumber service: ₦15,000–₦40,000 ($100–$200 in the US).
How to Prevent Future Leaks
- Clean faucets and spouts regularly to prevent mineral buildup.
- Avoid forcing the diverter lever—gentle use extends its life.
- If you have hard water, consider installing a water softener to reduce scale buildup.
- Replace washers and seals at the first sign of wear.
FAQs
1. Is it normal for a little water to drip from the tub spout when the shower is on?
A small trickle is normal, but a steady flow indicates a faulty diverter that needs repair or replacement.
2. Can I replace just the diverter instead of the whole faucet?
Yes. In most cases, you can replace the diverter valve or tub spout without changing the entire faucet system.
3. How long does a tub spout diverter last?
Typically 5–10 years, depending on water quality and usage.
4. Do I need to turn off the water supply to replace a tub spout?
No. For spout replacement, you usually don’t need to shut off water, but for valve or cartridge replacement, you must.
5. Should I hire a plumber for this repair?
If you’re comfortable with basic plumbing, replacing a spout diverter is DIY-friendly. For internal valve replacements, a plumber may be the better option.
Conclusion
If your bath faucet leaks while the shower is on, the diverter valve is usually to blame. In most cases, cleaning or replacing the diverter or swapping the tub spout will fix the problem. With the right tools, many homeowners can handle this repair themselves. However, if the faucet is old or the valve is inside the wall, hiring a plumber may be the best choice. Fixing the leak promptly will improve shower pressure, save water, and keep your plumbing system in good condition.