Your shower runs. The light comes on, water comes out. But the pressure has gone soft, and the temperature swings from lukewarm to cold no matter how you set it.
So you start thinking the worst. The heater’s dying. The whole thing is on its way out. You look up what a new one costs and the number stings. A new electric shower plus installation typically runs $320 to $1,150 (about £250 to £900), once you factor in a plumber’s time and any electrical work.
Here’s what almost nobody tells you before you spend that money. There’s a very good chance the shower itself is fine. Something small and clogged is choking off the water it needs to switch the heater on, and the shower is doing exactly what it was built to do about it.
You can check it yourself in about five minutes.
Why a cold shower isn’t what you think
An electric shower isn’t like a regular faucet. It pulls cold water straight from the pipe and heats it on the spot as the water flows past a heating element, kind of like water rushing through a running kettle. That element gets very hot, very fast, so it has to be protected. If the water flowing past it slows down too much, the shower shuts the heater off on purpose to keep the element from cooking itself.
That’s a safety feature, not a broken shower. Industry guidance from the UK’s Association of Manufacturers of Domestic Appliances (AMDEA) puts the numbers plainly: most electric showers need at least 14.5 PSI of running pressure and about 2 gallons per minute of flow (roughly 1 bar and 8 liters per minute) to work at full power (1).
When the flow drops under that, the low-pressure warning light on the front of most modern units clicks on and the heater goes dark. You still get water. You just get cold water, or water that keeps swinging between warm and cold. Feels like the whole thing has died. But the shower hasn’t broken. It’s protecting itself.
So the real question isn’t “is my shower dying?” It’s “what’s choking off the water?” And the answer is almost always somewhere between the wall pipe and the shower head, in a spot you can reach without touching anything electrical.
The three things quietly choking your shower
There are three usual suspects, and they usually build up together. Kohler-owned Mira, one of the biggest electric shower brands in the world, names all three directly in its own repair guides(2).
The shower head. Every time you shower, the water flowing through the tiny holes leaves behind a little mineral crust. When the shower switches off, some water dries inside the head and the crust builds up. Over months, that crust starts closing the holes down. Same pressure at the wall, way less water making it out the head.
The hose. The bendy hose that runs from the shower box to the shower head picks up the same crust inside. In hard-water areas (large parts of the American Midwest, Southwest, and Southeast, plus most of the UK and Ireland), a two- or three-year-old hose can be shockingly clogged.
The inlet filter. Most people don’t know this one exists. Inside the shower box, right where the cold water pipe enters, there’s a tiny mesh screen that catches grit and mineral bits floating in the water. Over time it clogs. When it does, the water slows down going in, the safety cutoff trips, and the heater stops firing. Mira’s own repair guide lists a blocked inlet screen as a direct cause of the shower running cold with the low-pressure light on.
Head, hose, filter. Three parts of one problem. All of them can be sorted out before you spend a penny on a new shower.
The 5-minute fix, in order
Do these in order. Safest and most likely first, then work inward.
- Soak the shower head. Unscrew the head from the hose. Drop it in a bowl of half warm water, half plain white vinegar for one to two hours, or overnight if you live in a hard-water area. Scrub the nozzles gently with an old toothbrush, rinse in hot water, and screw it back on. Independent industry guidance on shower repair notes this single step, on its own, fixes a large share of weak-flow and cold-water complaints on electric showers (3).
- Flush out the hose. With the head off, run the shower on cold only for about 30 seconds into a bucket. If little chunks of white gunk come out, keep running it. If the hose is old and heavily clogged, a new one costs around $13 to $20 (about £10 to £15) and swaps in a minute.
- Check the main water shutoff. Sometimes the flow has dropped because someone half-closed the whole-house cold water valve during other plumbing work. Make sure it’s fully open. Do the same for the little shutoff on the pipe going into the shower, if there is one.
- Reset the shower. Switch it off at the wall or ceiling switch, wait 30 seconds, then switch it back on. That resets an internal safety cutoff that sometimes stays stuck after a low-flow event.
Do those four things first. For a lot of “my shower’s gone cold” cases, that’s the entire fix. Full pressure back. Full heat back. Zero money spent.
When the fix goes deeper
If the shower still won’t heat after all four steps, the last thing to check before you replace the whole unit is that inlet filter inside the box. And here the job stops being safe DIY.
Both Mira and Triton (two of the biggest electric shower brands, with published US-market repair manuals) say the same thing in their own guides: cleaning that filter means taking the front cover off the shower box. Before you do, you have to switch the power off at the circuit breaker and shut the water off at the main, because the second the cover comes off, live electrical wiring is exposed (2, 4). Both brands say clearly this step should be done by a licensed plumber or electrician, not a general DIYer.
The good news: a plumber cleaning that filter is a small job, often under half an hour, and way, way cheaper than the $320 to $1,150 (about £250 to £900) you were about to spend on a whole new shower (5). If the mesh comes out looking chalky white, that was your problem all along.
Sources: (1) AMDEA, Electric Showers guidance; (2) Kohler Mira, Mira Go installation and user guide, cleaning the inlet filter and fault finding; (3) House of Enki, Why is my electric shower cold or not heating; (4) Triton, AGIO electric shower instruction manual, cleaning the inlet filter; (5) Trade2join, Electric shower installation cost in the UK 2026.
