Low Water Pressure in the Shower? Causes by Shower Type

If only the shower is weak and the taps are fine, the restriction is in the shower itself. The usual causes are a shower head or hose furred up with limescale, blocked filters where the pipes enter the valve, a thermostatic cartridge sticking with scale, a flow restrictor in the head, or an isolating valve that's only part open. Descale the head first, because in London's hard water that alone often fixes it. If every tap in the house is weak too, the problem is the water supply. If the shower has always been weak, it's usually down to the system: a tank-fed shower with little height to push the water, a combi boiler at its flow limit, or an electric shower on a poor mains supply.

Is it only the shower?

Before taking anything apart, run the nearest hot and cold taps. This one check decides where to look.

• Taps fine, shower weak: the problem is in the shower head, hose, valve or the pipe feeding the shower. Start with the checks below.
• Every tap and shower weak: it's the supply to the house or to the tank. See our guide to low water pressure in your home, which covers the stopcock, old lead and iron pipes and Thames Water supply issues.
• Only the hot is weak, everywhere: it's the hot water system rather than the shower.
• Weak only when another tap or the washing machine is running: the supply is shared and can't meet both demands. That's a flow rate problem, common in flats and with combi boilers.

Checks you can do yourself

1. Descale the shower head. Unscrew it and soak it in white vinegar or a descaler for a few hours, then rub the rubber nozzles to push out the scale. If you can't remove it, tie a bag of vinegar around it. A heavily scaled head can cut the flow dramatically.
2. Check the hose. A kinked hose, or one whose inner lining has collapsed, restricts flow. Take the head off and run the shower through the hose alone. If the flow is strong without the head, the head is the problem. If it's still weak, look further back.
3. Look for a flow restrictor. Many water-saving heads and some hoses have a small restrictor fitted. If the head is new and the shower got weaker when you fitted it, that's the likely reason.
4. Open the isolating valves. Many shower valves have isolating screws in the inlet elbows or small valves on the pipes. If someone has part closed one, the shower will be weak on that side. They should be fully open, with the slot in line with the pipe.

If none of that helps, the next suspects are inside the valve. Most bar and concealed valves have small mesh filters on the hot and cold inlets that trap scale and debris. A thermostatic cartridge can also scale up until it can't open fully. Cleaning the filters means isolating the water to the shower, and changing a cartridge means taking the valve apart, so if there are no isolating valves on the supply, leave it to a plumber. If the shower is also running too cold, our guide to no hot water in the shower goes through the cartridge in more detail.

What your shower type can deliver

Some showers are weak because of a fault. Others were never going to be strong on the system they're connected to.

Shower type	Where the pressure comes from	Typical reason it's weak
Mixer on a tank-fed (gravity) system	The height of the loft tank above the shower head	Little height between tank and head, especially in top-floor bathrooms and loft conversions
Power shower or pumped mixer	A pump boosting tank-fed water	A worn or failing pump, or a low tank
Mixer on a combi boiler	The mains	Low mains flow, the boiler's hot water limit, or other outlets running at the same time
Mixer on an unvented cylinder	The mains	Low incoming mains, or a fault on the cylinder's inlet controls
Electric shower	The mains cold supply	Low mains flow, scale in the unit, or cold incoming water in winter

Tank-fed showers

On a gravity system, the pressure at the shower depends almost entirely on how high the cold water tank sits above the shower head. A tank in the loft above a first-floor bathroom gives a modest shower. A shower in a loft conversion, where the head may be level with the tank, can barely run at all. That's the design, not a fault.

This is where a shower pump helps. It boosts the tank-fed hot and cold to the shower, and a power shower combines a pump and mixer in one unit. Our shower pump and power shower services cover both, and our guide to shower pump problems covers pumps that have started to fail. A pump needs a big enough tank and hot cylinder behind it, or it will empty them quickly.

If a tank-fed shower has got weaker over time rather than always being weak, check the loft tank is filling properly. A sticking float valve that lets the level drop will weaken every tank-fed outlet.

Combi and mains-fed showers

With a combi boiler, the shower runs at mains pressure, but the amount of hot water is limited by what the boiler can heat as the water passes through and by how much water the mains can supply. Run a second tap or the washing machine at the same time and the shower drops. Scale inside the boiler's hot water heat exchanger can reduce the flow further over the years, which a service can pick up. Our guide to combi vs system boilers explains the limits of each.

Don't fit a shower pump to a combi or any mains-fed shower. Shower pumps are made for tank-fed water and must not draw directly from the mains. If the mains itself is poor, the answer depends on why: an old lead or iron supply pipe, a part-closed stopcock or a weak supply in the street. Our mains water pressure service starts with measuring what's coming in. Any mains booster or storage system has to be designed to comply with the water regulations and your water supplier's rules.

If you have an unvented cylinder and the hot side is weak, see our guide to low hot water pressure from an unvented cylinder.

Electric showers

An electric shower heats cold mains water as it flows through, so it can only run as fast as it can heat. In winter the incoming water is colder, and the shower slows the flow to reach the same temperature. Some drop in winter flow is normal. A sudden or large drop usually means scale in the spray plate or inside the unit, or a problem with the mains cold supply to it. If the shower is old and weak all year, a higher-rated replacement may help if your electrics can support it. Our electric shower installation service covers that.

When to call a plumber

Call a plumber if the shower is still weak after cleaning the head and hose, if the valve filters or cartridge need attention and you have no isolating valves, if you're thinking about a pump and aren't sure your system suits one, or if the whole house is weak. We'll check the supply, the valve and what the system can realistically deliver before suggesting anything.

We charge £95 an hour for labour, plus a £60 call-out that's waived when the job runs over 2 hours. Parts are extra and we confirm the price before any work starts. Our shower repair service covers valves, cartridges and pumps across London, and the pricing page explains how jobs are charged.

Frequently Asked Questions