Low Water Pressure: Which Taps and Showers Will Work?

Pressure problems start with the system, so look in the loft and the airing cupboard:

Many older homes have gravity hot water but mains-fed cold, so the two sides of a mixer arrive at very different pressures — check what a tap or shower valve needs on each side before you buy. Our boiler guide explains the systems in more detail.

On a gravity system the pressure comes from height alone. The rule of thumb is that every 10m of height — called head — gives about 1 bar, or 0.1 bar per metre, measured from the water level in the cold tank down to the tap spout or shower head.

That's why an upstairs shower on a gravity system is so often weak. Raising the cold tank on a sturdy, properly supported platform helps a little: every extra metre adds another 0.1 bar.

Pressure, in bar, is the push; flow, in litres a minute, is what you actually feel. You can measure flow with a bucket and a stopwatch:

1. Take a bucket or jug with a known volume — a 10-litre bucket is ideal.
2. Open the tap or shower fully and start timing as the water goes in.
3. Stop when it's full and work out litres ÷ seconds × 60. 10 litres in 50 seconds is 12 litres a minute; 10 litres in 2 minutes is 5.
4. Test the kitchen cold tap too. It's normally fed straight from the mains, so it shows what the mains can deliver.

For a pressure reading, a tap-on gauge on the kitchen or outside cold tap shows the mains pressure. Before blaming the supply, make sure the stop tap and any isolating valves are fully open, and descale a blocked aerator or shower head — both are common causes of a weak flow from a good supply.

It depends on the tap, so check its minimum working pressure in the product details or instructions. Many modern single-lever mixers are designed for combi and unvented systems: the Grohe Essence basin mixer we sell, for example, works from 1.0 bar. That's fine on a combi, but it's 10m of head — far more than a gravity-fed bathroom gets.

On a gravity system, choose taps rated for low pressure, with a minimum working pressure at or below what you have at that outlet. Traditional pillar taps, with a wide waterway and no mixing cartridge, are usually the most forgiving. Not sure what a tap needs? Ask at the counter with your system type and we'll check the maker's figures.

An electric shower's flow is limited by its power rather than the pressure: a 9.5kW shower heats roughly 4.5 litres a minute through a 30°C rise, less in winter when the incoming water is colder. It's the simplest fix where the hot water is tank-fed, as long as the mains meets the shower's minimum pressure. A new electric shower needs its own circuit from the consumer unit, which is notifiable under Part P in England, so it's a job for a registered electrician.

When both the hot and the cold come from tanks — a cold tank in the loft feeding a vented cylinder — a shower pump turns a weak shower into a strong one. A twin-impeller pump boosts hot and cold separately before they reach the mixer valve; a single-impeller pump boosts one supply, or the mixed water after the valve.

Pump makers usually ask for a dedicated hot feed from the cylinder, often through a special flange, so the pump doesn't draw air. If the shower head is level with or above the water in the cold tank, there isn't enough gravity flow to start a standard pump, and you need a negative-head pump.

Browse shower valves and kits, mixer taps and shower heads, or bring your old cartridge or valve to the counter and we'll match it.