Quick Answer:
If your shower won’t shut off completely, first make sure the handle is fully in the off position. If that doesn’t stop the flow, remove the handle to check the set screw or adapter, and look for a worn or stuck cartridge that needs replacing. If you can’t stop the water at the fixture, use the main shutoff valve and elect to completely shut off water to your house as a temporary measure before getting professional help.
Why This Happens
- Worn cartridge, seal, or O-rings inside the valve allow water to pass even when the handle is “off.”
- Loose or broken handle hardware (set screw or adapter) makes the handle look off when the valve is still partly open.
- Mineral buildup or corrosion can prevent the cartridge or stem from seating properly.
- Internal valve parts can break or shift, keeping a small flow even with the handle in the off position.
Step-by-Step What to Do
1. Confirm the handle is in the off position
Turn the handle firmly to the off position and try both hot and cold stops. Some mixers have separate stops for hot and cold — check both. If the flow reduces but doesn’t stop, move to the next step.
2. Remove the handle to check the set screw and adapter
- Look for a small cover or cap on the handle; prying or pulling it off will expose the set screw.
- Loosen the set screw and remove the handle to inspect the cartridge adapter or splined stem. The adapter can shear, strip, or sit loose so the handle turns without moving the cartridge fully.
- If the adapter or screw is broken or worn, that can explain why the handle doesn’t fully stop flow.
3. Identify common cartridge symptoms
- Steady drip or trickle when handle is off — worn seals or a damaged cartridge.
- Water only stops when handle is turned a specific way — sticking or partially seized cartridge.
- Handle turns but nothing changes — stripped adapter or detached stem.
- Visible corrosion or mineral build-up around the valve body or cartridge.
4. Use the main shutoff if needed
If you cannot stop the water at the valve, close the main shutoff valve or the home’s primary supply to stop flow to the fixture. After shutting off, open the shower to relieve pressure and drain remaining water before you inspect or remove parts.
5. Temporary steps to stop water safely
- Close local isolation valves if you have them (some showers have shutoffs behind access panels). If none, use the main shutoff.
- Place a bucket or towels to catch water if a small leak continues while you organize repairs.
- Turn off or isolate nearby electrical outlets or devices if water is reaching them; move rugs and electronics away from the area.
- Once the water is off, do not operate the valve further without inspecting and replacing worn parts — leaking can get worse if seals are damaged.
What Not to Do
- Do not force the stem — forcing can break the cartridge or housing and make repairs more expensive.
- Do not keep tightening random screws — overtightening can strip adapters or crack trim parts and will not fix a worn cartridge.
- Do not leave the shower running if you can’t stop it reliably — uncontrolled leaks risk water damage and mold.
When to Call a Professional
- When you can’t stop the water after checking the handle and attempting the main shutoff.
- If the cartridge, valve body, or plumbing behind the wall appears corroded, cracked, or damaged.
- When you don’t have an access panel or are uncomfortable removing the valve components — a plumber can safely replace the cartridge and check the hidden plumbing.
Safety Notes
- Shutting off water to the house is the safest temporary step if the fixture won’t stop. After shutting off, relieve pressure by opening faucets.
- Avoid working on the valve with electrical devices nearby. Water and electricity are a dangerous combination.
- If you smell gas or see obvious structural damage from water, evacuate and call emergency services or a professional immediately.
Common Homeowner Questions
- Why does my shower drip even when off? Worn seals or a damaged cartridge usually allow a slow drip when the valve can’t seat.
- Can I replace the cartridge myself? Yes, if you can access the valve and match the part; otherwise call a plumber to avoid making it worse.
- Is it safe to just leave the water shut off until a plumber arrives? Yes — shutting the water off and draining the fixtures is the safest temporary solution to prevent damage.