Bath Shower Mixer Won't Switch to Shower
- How urgent
- Low risk
- Who fixes it
- A plumber
What's happening?
On a bath-shower mixer, a diverter sends water either to the bath spout or up to a hand shower. A pull-up knob lifts a plunger that blocks the spout, or a lever turns a valve that does the same. If the diverter will not stay up, the water pressure behind it is pushing it back down, or the seal is worn so some water still leaves through the spout. If it will not move at all, scale or grit has locked it. If the shower dribbles while the spout runs, the diverter is passing water in both directions. The fix depends on the symptom, so note exactly what it does when you operate it.
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What usually causes it?
- A worn washer or seal on the diverter plunger, so water leaks past it
- Scale or grit locking the diverter in one position
- Low pressure on the hot or cold side that cannot hold the diverter up
- A broken diverter part, such as a plastic lug or the return spring
- A blocked shower hose or head, making back pressure that drops the diverter
- A cartridge-type diverter that has worn and no longer shuts off the spout
- A mixer designed for high pressure fitted on a low-pressure supply
Is it dangerous?
No. If the diverter drops back when you turn on the hot, you may be scalded by a spout that suddenly runs hotter than the shower, so check the temperature before stepping under. A diverter stuck so that water runs to the shower only means the bath cannot be filled.
Can I fix it myself?
Watch what the diverter does with the water running. If it drops back with the hot turned on, the problem may be low hot pressure, so test with the cold only. Descale the shower hose and head, since a restricted hose raises back pressure. Many diverters unscrew from the top of the mixer; shut the supply, lift out the cartridge or the plunger and replace its washer or the whole part, matching the maker and model. Crosswater shows how to replace or service a diverter valve. Do not use jointing compound on a diverter that is meant to slide.
When should you call a plumber?
Call a plumber when the diverter part is not available as a separate item, when the mixer is wall-mounted or concealed, when the supply is too weak to hold it, or when replacing the washer or cartridge has not helped.
What will the plumber actually do?
- Identify the mixer make and the diverter type, pull-up, lever or cartridge
- Isolate the supply, lift out and inspect the diverter and replace its seal or cartridge
- Check the hose and shower head for restriction
- Measure the pressure and flow on hot and cold
- Replace the mixer or fit a pump where it cannot work on the existing supply
Who fixes this
What it usually costs
- Bathroom Installation Cost
- Priced on survey
Questions people ask
Why won't my bath tap switch to the shower?
Why does the diverter drop when I turn the hot on?
Can I replace the diverter myself?
Why does water come from both the spout and the shower?
Sources & References
Before you book, read what to check before a plumber starts.
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