Fix low pressure in a shower

Diagnose and clear common causes of weak shower pressure, from limescale to airlocks, before calling a plumber.

LP-01Work out if it's just the shower or the whole houseTurn on the kitchen tap and another tap in the house. If they're all weak, the problem is with your water system, not the shower itself. If only the shower is weak, the fault is local to the shower head, hose, or valve, and the rest of this guide will fix it.

LP-02Identify your water system typeCheck your airing cupboard or loft for a cold water storage tank feeding a hot water cylinder. This is a gravity-fed system, common in older houses, and it's naturally lower pressure than a mains-fed combi boiler or unvented cylinder. Knowing which you have explains why some fixes apply and others don't.

LP-03Find your stopcock and isolate the waterFind your stopcock, usually under the kitchen sink, and check it turns before you start. Turn it off fully clockwise so no water sprays out when you loosen the shower fittings. If you have an electric shower, also switch off its isolating switch, usually a pull-cord or wall switch outside the bathroom, before touching the head or hose.

LP-04Clean the shower headUnscrew the shower head and soak it in limescale remover for 20-30 minutes. Scrub the nozzles with an old toothbrush and use a pin to clear each hole individually. A clogged head is the single most common cause of weak spray, especially in hard water areas.

1 each · Limescale remover (500ml)

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1 each · Old toothbrush

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1 each · Fine pin or needle

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LP-05Check the shower hoseDetach the hose from the bracket and mixer, and run it under a tap into a bucket to check the flow is even along its full length. Look for kinks, flat spots, or bulges in the outer casing. Replace the hose if it's perished or restricted anywhere.

1 each · Replacement shower hose

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1 each · Adjustable spanner

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LP-06Clean the inlet filters at the valveWith the water still off, unscrew the flexible tails or hose connections at the mixer or shower valve. Most have a small plastic mesh filter washer just inside the connection. Pull it out with pliers, rinse off the limescale and debris, and refit, or replace it if it's damaged.

1 pack · Replacement filter washer set

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LP-07Check the isolating valves are fully openLook for small service valves on the pipes feeding the shower, often behind a bath panel or access hatch. These have a slotted screw or lever that should sit in line with the pipe when open. A valve left half-closed after previous work is an easy thing to miss.

LP-08Clear an airlock, if you have a gravity-fed systemIf you found a cold water tank in step 2, check the tank isn't low or the float valve stuck, then top it up if needed. Run the shower and a nearby cold tap together for a minute to help push any trapped air through the pipework.

LP-09Rule out a whole-system pressure problemIf every tap in the house is weak even after checking the above, the fault likely sits with the mains supply, the stopcock not being fully open, or the hot water cylinder itself. Don't attempt to adjust or open an unvented cylinder yourself.

RULES

KNOW THE RULES

Work on an unvented (pressurised) hot water cylinder must be carried out by a Building Regulations G3-competent engineer. This is a legal requirement, not just good practice.

LP-10Check an electric shower safelyWith the isolating switch off, check the incoming cold water pressure meets the manufacturer's minimum for your model, often printed inside the unit's cover or in the manual, since electric showers need a minimum flow to fire the heating element. Don't remove the front cover or touch any wiring yourself.

RULES

KNOW THE RULES

Any work inside the electric shower unit or its fixed wiring counts as electrical work in a bathroom special location under Part P of the Building Regulations. Use a qualified electrician; this guide covers checks only.

LP-11Reassemble, test, and tidy upWrap the hose and mixer threads with fresh PTFE tape before refitting the head and hose. Turn the stopcock and any electrics back on, then run the shower for a few minutes to check pressure has improved and there are no leaks at the joints. Wipe down the tiles and dispose of any old descaler solution down the drain with plenty of water.

1 roll · PTFE tape

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