A leaky shower faucet most often needs a new cartridge, the cylinder inside the valve that controls flow and temperature. When a drip continues after the cartridge is replaced, the valve body or its seats are worn, and that repair can mean opening the wall. A drip that shows up on a ceiling or wall nearby may be a leak in the pipes and not the faucet at all.
This guide explains how to tell the cases apart, what a cartridge swap involves, how plumbers get to the valve and when to stop and call. If the water will not shut off at all, close the main water valve first.
What a dripping shower is telling you
Where the water appears points to the cause. Use this as a starting guide before you take anything apart.
- Dripping from the showerhead after the handle is off usually means a worn cartridge or valve seat.
- Dripping from the tub spout while the shower is running is the diverter, which is a separate part.
- Water leaking around the handle means a worn seal or a loose stem.
- Hot or cold water seeping into the wrong side points to a failing cartridge or stop.
- Stains on a ceiling or wall near the shower point to a leaking pipe or fitting behind the wall.
A showerhead that drips a few drops after use is a different matter. Water trapped in the head often drains for a minute and then stops. A constant drip that keeps going is the one to fix.
Cartridge, valve or something else
The cartridge is the working part. It slides or turns inside the valve body as you move the handle. The valve body is the brass or plastic housing set in the wall, and it connects to the supply pipes. Most leaks start with the cartridge, because it has the moving seals.
| Problem | Likely part | Access needed |
|---|---|---|
| Constant drip from head | Cartridge or seats | Through the handle opening |
| Handle leaks at the base | Stem seal or O-ring | Through the handle opening |
| Water will not shut off | Cartridge, stop or valve | Handle opening, sometimes the wall |
| Drip persists after new cartridge | Valve body or seat | Often wall access |
| Leak inside wall or ceiling | Pipe or fitting | Wall or ceiling access |
| Tub spout runs with shower on | Diverter | Spout or wall access |
Replacing a shower cartridge
Many cartridges can be replaced from the front, without opening the wall. A plumber will normally do these steps.
- Shut off the water at the shower stops if there are any, or at the main valve.
- Remove the handle by loosening its set screw or cap, then remove the trim plate.
- Take out the retaining clip or nut that holds the cartridge in place.
- Pull the old cartridge straight out, using the right puller if it is stuck.
- Inspect the valve body for scale, scoring or cracks.
- Install a matching new cartridge, replace the clip, reinstall the trim and test.
Take the old cartridge to the supply house or photograph it before ordering. Many look alike but are not interchangeable, and the wrong one will leak or run backward with hot and cold swapped.
A cartridge that will not budge is common in older showers. Scale locks it in place, and forcing it can break the valve body. If it does not move with moderate effort, stop and call a plumber.
When the valve itself is the problem
If a new cartridge does not stop the drip, the valve body may be worn, scored or cracked. Mixed-material valves and very old valves can also have seats that no longer seal.
The fix is to replace the valve. That means reaching it, cutting the supply pipes, soldering or connecting a new valve and testing the joints. It is a plumber's job because a bad connection in a wall leaks where nobody sees it.
A good plumber checks the old valve and tells you which repair is needed before cutting anything. Our faucet repair page explains how we handle cartridge and valve replacement.
Wall access: what to expect
Valves are set between the wall studs, and replacement often needs access from one of two sides. The plumber may go through an access panel on the back of the wall, which is common when the shower backs onto a closet, bedroom or utility space. Or the plumber may open the shower wall itself.
Tile and surround repair come after the plumbing work, and the plumber should tell you ahead of time who handles the wall finish. If the valve is in a hard-to-reach spot, a plumber may suggest cutting from the back and patching drywall instead of removing tile.
If you have a panel behind the shower, tell dispatch when you call. If you do not, a plumber can look at the wall layout and tell you what is least damaging.
Safe steps for a shower that will not shut off
Close the shower's stop valves if it has them, or close the main water valve where the line enters the house. Open the lowest faucet to drain the pipes, then check that the drip stops. Keep towels on the floor, and move electronics and rugs away from wet areas. If the water is coming through a ceiling, turn the water off at the main and keep people away from the wet area.
Signs the leak is bigger than the faucet
A shower valve is only one place water can escape in a bathroom. Stop and call a plumber if any of these show up.
- A stain or soft spot appears on a nearby wall or ceiling.
- The floor around the tub feels damp or the paint bubbles.
- Water pressure drops at other fixtures.
- Your water bill rises and the meter turns when everything is off.
- A musty smell comes from the wall.
If you suspect a hidden leak, stop guessing. Our leak detection page covers how plumbers find water inside walls without tearing out more than necessary.
If the water will not shut off in Kuna
The City of Kuna lists a Water Department emergency number at (208) 573-7676, and staff are on call around the clock for water and irrigation emergencies. If your house shutoff fails, that number is where to ask about the city side of the line.
That is useful because a shower that will not stop is often fixed by closing the valve at the house, and the city line is the next step only when the house valve will not close. Know where your main valve is before you need it.
Whatever is wrong behind the shower wall is still a plumber's job. The city can only help with its own side of the meter.
Source: City of Kuna Water Irrigation page
Shower leaking or will not shut off?
Call (208) 679-8357 any hour. Tell dispatch the handle style, where the water shows and whether the main valve closes.
Serving Kuna and neighboring towns
We handle shower valve and cartridge work in Kuna and for callers reaching us from Nampa and nearby towns. Our service area page lists the towns we cover, which is useful if you are not sure about your address. Replacing a shower valve, as opposed to a cartridge, is plumbing work under the 2017 Idaho State Plumbing Code, based on the 2015 UPC.
Frequently asked questions
A worn cartridge or valve seat is the usual cause. Over time the seals harden or the seat gets scored, and water slips past even when the handle is off.
Sometimes the cartridge can be replaced through the handle opening. If the valve body itself must be replaced, the plumber usually needs access from behind or through the shower wall.
A slow drip can wait for a planned visit, but it wastes water and can stain the tub. If the drip is increasing or water shows on a wall or ceiling, call sooner.
Yes. A plumber can remove the damaged handle, replace the cartridge or stem and fit a new trim. Bring the make and model if you can find it.
Close the main valve first. If the main will not close, the City of Kuna lists a Water Department emergency line at (208) 573-7676, and then call a plumber for the repair.
A drip from the head is a reasonable DIY try if you have the right cartridge and can shut the water off. Stop if the cartridge is stuck, the valve is cracked or the leak is inside the wall.