How to Fix a Leaking Bathtub Faucet
Most tub faucet drips are cartridge or compression-stem failures. The fix is similar to shower valves.
TL;DR
Bathtub faucets use the same cartridges as shower valves. Identify the brand, shut off main water, remove handle and trim, swap cartridge. The added complexity vs shower: tub spouts may also leak (different fix — replace the spout).
What’s in this guide
- Diagnose: spout vs handle leak
- Tools
- Disassembly
- Cartridge replacement
- Spout replacement
A leaking bathtub faucet usually drips from one of two places: the tub spout (water comes out even when the diverter is engaged) or behind the handle (drips inside the wall, often visible as ceiling stain in the room below). Both have specific fixes.
Tools & Materials You’ll Need
Tools
- Allen wrench set
- Phillips and flathead screwdrivers
- Channel-lock pliers
- Plumber’s tape
- Cartridge puller (brand-specific)
- Towel
Materials
- Replacement cartridge (brand-specific) $15–$45
- Replacement tub spout if needed ($25–$60)
- Plumber’s grease
Step-by-Step Instructions
Determine: Spout Drip or Handle Leak?
If water drips from the tub spout when the shower is engaged (diverter pulled up), the spout diverter has failed — replace the spout. If water drips from the spout with everything off, or you see water at the handle/trim, it’s a cartridge issue.
Replace the Spout (Spout Diverter Issue)
Look at the spout: slip-on (held by setscrew under the spout) or threaded (twists off). For slip-on, loosen the setscrew with an Allen wrench, slide spout off. For threaded, unscrew counter-clockwise. Apply plumber’s tape to the new spout’s threads, install. Tighten by hand + 1/4 turn with channel locks.
Cartridge Replacement (Handle Leak)
Same procedure as shower cartridge replacement: shut off main water, remove handle, remove trim, extract old cartridge, install new. See our shower faucet guide for detailed steps. The valve body in tubs is identical to showers.
Test and Verify
Restore main water. Test cold, hot, and mix through the handle. Pull diverter up and verify water flows from showerhead with NO drip from spout. Wait 30 minutes and check trim plate for any moisture.
Tub spout diverter failure is one of the most common shower complaints we hear: “the shower works but water still comes out the tub.” 95% of the time it’s a $30 spout replacement that takes 15 minutes. Don’t pay $185+ for a service call before checking the spout.
Don’t over-tighten the new spout
Cracking the wall pipe behind the spout is a major in-wall repair. Hand tight + 1/4 turn is enough.
Real Scenarios from Our LA Service Calls
$30 fix the homeowner’s plumber missed
Homeowner was quoted $850 for “complete tub valve replacement” by another plumber for what turned out to be a failed spout diverter. We arrived for a second opinion, replaced the $30 spout in 12 minutes, and the problem was solved.
When to Call a Plumber Instead
DIY isn’t always the right call. Bring in a licensed plumber if any of these apply:
- Leak is inside the wall behind the tub
- Cartridge won’t come out after vinegar soak
- Multiple repairs have failed
- You’re uncomfortable shutting off the main water
Frequently Asked Questions
How long does a tub faucet cartridge last?
5–8 years in hard SFV water. 10–15 years coastal LA.
Can I just replace the entire valve?
Yes but it’s a major job — requires opening the wall behind the tub. $1,200–$2,200. Cartridge replacement at $185–$385 is much more economical for most issues.
Why does my tub spout drip after I take a shower?
Residual water in the spout drains for 30–60 seconds normally. If it continues, the diverter is stuck partially open or broken — replace the spout.
My tub fills slowly even with both handles fully open — why?
Either galvanized supply scaling or aerator-equivalent buildup in the diverter assembly. Bring spout to plumber for inspection.
Can I replace the tub spout with a different style?
Yes, as long as the connection type matches (slip-on vs threaded) and the length is adequate to clear the tub edge.
Need professional help in Los Angeles?
Same-day service. Flat-fee pricing. No surprise add-ons.
Call (818) 938-8660
