Simple guide to understanding hot water pressure in your home

Before purchasing taps or shower heads, it’s important that you understand water pressure systems, and which type you have in your home.

The wrong combination of water pressure systems and taps/showers may result in:

  • Low water pressure
  • Poor shower experience, and;
  • a bath that takes a long time to fill

This short guide will explain to you in simple terms what type of hot water pressure system you have and how that affects the pressure at your tap.

Which water pressure system do I have?

Most households have one of the three water pressure systems outlined below and by following our guidance you’ll easily be able to discover which system you have.

Gravity-fed system

One of the most common systems in the UK is the gravity-fed system, mostly due to its low-cost installation. To see if you have a gravity-fed system, you’ll likely have:

  • a hot-water cylinder (most likely in airing cupboard)
  • a cold-water tank in the loft

If you can get up into your loft, take a look and see if there is a tank with water in.

The way that gravity-fed systems work is rather simple – they use gravity to create pressure. Cold water in the loft/attic feeds into the hot water tank, which heats up the water and distributes it around the house.

Gravity-fed systems are in most cases considered low pressure, but there is a rather simple way you can test the pressure of your hot water.

To test the pressure of a shower, you need to measure the distance between your cold-water tank in the loft and your shower head. You don’t need to be accurate to the millimetre – you can measure from your shower head to the ceiling and then from the floor of your loft to the bottom of your tank (you can do the same to measure taps around the house).

1 metre is equal to 0.1 bar of pressure, 2 metres is equal to 0.2 pressure and so on. Anything under 1.0 bar of pressure is considered a low-pressure system – so when shopping for taps and shower heads it’s important that you purchase products designed for low-pressure systems. It’s also common for a shower pump or an electric shower to be installed when using a low-pressure water system.

Combi-boiler system

If there is a combination (combi) boiler in your home, then you have a high-pressure vented water system. A combi boiler removes the need for cold water tanks and hot water cylinders.

Mains water pressure that comes into your house, goes straight into a combi boiler which heats and pumps hot water around your house.

The pressure from combi-boiler systems is very close to mains water pressure – making it a high-pressure system.

Being a high-pressure system, a combi boiler will give you more flexibility when purchasing showers or taps, as most will be suitable.

High-pressure unvented water system

If you have a hot-water tank (most likely in airing cupboard) but not a cold-water tank, then you have a high-pressure unvented water system.

Water is stored at mains pressure in the tank and is heated by immersion heaters or a central heating boiler.

Just like combi boilers, these can work with most taps and shower heads, with no problems.

Do I need a low-pressure shower head or taps?

Unless you have a gravity fed system, then it’s most likely that you don’t need to purchase products designed for low pressure.

If you do have a gravity-fed system, then it’s advisable to spend some time and pick the best shower head for low water pressure.



Sign up to receive tips on reducing your energy & water bills, new product news & more.