Plumbing service
Shower and bathtub plumbing
Short answer
Most shower and tub problems come from the valve hidden behind the handle: a worn cartridge or washer makes the shower drip, a failing pressure-balancing part causes sudden hot and cold swings, and scale makes handles stiff. Replacing the cartridge fixes most of them. Leaks behind the wall, a failed shower pan or a corroded valve body mean opening the wall.
Updated · Editorial team; not yet technically reviewed
Shower & Bathtub Plumbing at a glance
- Most common fix
- Replacing the valve cartridge, which is matched to the valve's brand and model.
- Hot-and-cold swings
- A worn pressure-balancing spool or a scaled cartridge.
- Dripping after shutoff
- Worn cartridge seals or seats; it wastes water constantly.
- Water on the ceiling below
- Test the shower, the tub and the drain separately. See water leaking from the ceiling.
Symptom, cause and fix
| What you notice | Likely cause | Usual repair |
|---|---|---|
| Shower head drips after you turn it off | Worn cartridge seals, washers or seats | Replace the cartridge or the washers and seats on older two-handle valves |
| Water suddenly turns hot or cold when someone flushes | Pressure-balancing spool stuck or worn | Clean or replace the cartridge; older valves without balancing can be upgraded |
| Weak flow at the shower only | Clogged shower head, or scale in the cartridge | Descale or replace the head, then the cartridge |
| Water still comes out of the tub spout when the shower runs | Worn diverter in the spout or valve | Replace the spout or the diverter cartridge |
| Handle hard to turn | Scale on the cartridge | Replace the cartridge; consider water treatment in hard-water areas |
| Tub drains slowly | Hair and soap on the stopper linkage or in the trap | Clean the stopper and trap, then clear the drain line |
What's inside a shower valve
A single-handle shower valve has a brass body set in the wall, with a replaceable cartridge that mixes hot and cold water. Since the late 1990s, most codes have required pressure-balancing or thermostatic valves in showers, which protect against sudden temperature changes when water pressure shifts elsewhere in the house.
Older homes may still have two- or three-handle valves with rubber washers and brass seats. Those wear predictably, and the seats can be replaced through the handle openings without opening the wall.
Valve cartridges are brand-specific. Knowing the faucet brand, or photographing the trim and handle, helps a plumber bring the right part on the first visit.
When the problem is behind the wall
- Leaking valve body or supply connection: water appears below the shower even when it hasn't been used. That's pressurized water and needs prompt repair.
- Failed shower pan: water shows up below only after showers, often at the edge of the room under a tiled shower.
- Tub overflow or drain gasket: leaks only when the tub is filled high or drains.
- Corroded or obsolete valve: if parts aren't available, the valve body is replaced, which means opening the wall, ideally from a closet behind the shower rather than through the tile.
Replacing a valve during a remodel
If the wall is open for new tile, it's the right time to replace an old valve, add a thermostatic or pressure-balancing valve, or move the shower head. Valve replacement usually needs a permit and inspection in most cities. See bathroom remodel plumbing for how remodel plumbing is planned.
What affects the cost
- Cartridge replacement versus replacing the valve body in the wall
- Access: a closet behind the shower versus opening tile
- Valve brand and part availability
- Water damage repair if a leak has gone on for a while
We don't publish prices; they vary by market. Get a written quote first.
Common questions
How long does a shower cartridge replacement take?
Usually under an hour once the right cartridge is on hand. Stuck cartridges in hard-water areas can take longer to remove without damaging the valve.
Why does my tub spout drip even with the water off?
A worn valve cartridge or seat lets water past. The spout is just the lowest outlet, so the drip shows there first.
Is a dripping shower worth fixing quickly?
Yes. A steady drip wastes a surprising amount of water and usually gets worse as the seals wear further.