Stop using the shower or bath if water is reaching ceilings, walls or electrical fittings
Isolate local water supplies where possible. Electric showers must be isolated electrically before any internal work, and temperature faults that create scalding risk should be treated as urgent.
MOST LIKELY CAUSES
Start with these
Symptom variations Match the exact pressure, temperature or leak pattern. ⌄
- Shower is too hot at every setting
- Cold taps elsewhere are normal
- Temperature control has little effect
- Problem started after repair work
- Flow reduces when turning colder
Quick checks Simple checks before dismantling shower or bath components. ⌄
- Identify whether the problem affects pressure, temperature, drainage or leakage.
- Check nearby hot and cold outlets for similar symptoms.
- Clean accessible shower heads, filters and waste covers.
- Inspect hoses, seals, trays and accessible joints.
- Stop testing immediately if water appears below or near electrics.
Step 1 — Stop using the shower if scalding Use controlled tests and stop if water reaches ceilings or electrics. ⌄
Process
Do not continue testing with unsafe temperatures.
Step 2 — Check cold supply elsewhere Use controlled tests and stop if water reaches ceilings or electrics. ⌄
Process
Run a nearby cold tap and inspect local shower valves.
Step 3 — Check accessible cold-side valve Use controlled tests and stop if water reaches ceilings or electrics. ⌄
Process
Confirm it is open without forcing it.
Common causes explained Why shower and bath faults develop. ⌄
A hot-only shower usually has a restricted or missing cold supply, blocked cold filter, closed valve, stuck thermostatic cartridge or reversed connection.
Shower and bath faults often depend on when water is flowing, draining or hitting a sealed surface. Controlled separate tests help distinguish supply, mixer, waste and enclosure faults.
Advanced diagnostics Plumber or appliance-engineer checks. ⌄
- Clean cold inlet filter and check valve.
- Replace thermostatic cartridge.
- Verify supply connections and direction.
- Measure hot and cold dynamic pressures.
- Calibrate thermostatic mixer after repair.
Parts that may need replacing Common components linked to this fault. ⌄
- Thermostatic cartridge
- Inlet filter
- Check valve
- Service valve
- Mixer connection component
When to call a plumber or engineer Conditions that should end basic troubleshooting. ⌄
- Water is leaking through a ceiling or near electrical equipment.
- The shower temperature is dangerously hot or unstable.
- An electric shower has an internal heating or power fault.
- The tray, bath or concealed pipework must be removed for access.
- A thermostatic cartridge cannot be calibrated safely.
- The fault returns after basic cleaning or seal replacement.
Frequently asked questions Common questions about shower and bath faults. ⌄
Why does a shower drip after it is turned off?
Large heads and hoses can hold water temporarily. Continuous fresh dripping points to a leaking control valve or cartridge.
Can failed sealant cause a ceiling leak?
Yes, but waste joints, pipe connections and tray movement must also be ruled out.
Why does shower temperature change when another tap is used?
The hot and cold pressures may be unbalanced or the thermostatic cartridge may not compensate correctly.