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How to increase water pressure in a shower with a combi boiler

someone washing hands under a running tap

Homeowners often look for ways of increasing the water pressure in their homes, particularly in the shower.

The available options to achieve this depends on the type of boiler they have. If you have a combi boiler, your options for increasing the pressure in your shower are limited, and you should consider consulting with a professional Gas Safe registered engineer to find the most suitable option for you and your home.

Below you will find a short explanation into combi boilers and the alternative options you have to increase the pressure of your shower.

Boiler pressure and combi boilers

To understand how to increase water pressure in a home with a combi boiler, we must first understand how a combi boiler works. Combi boilers are a type of boiler that can provide both hot water and central heating in a single, compact system. They combine the components of a traditional central heating system (i.e. a hot water cylinder and a cold water storage tank), hence ‘combi’ or ‘combination’.

Combi boilers receive water directly from the mains and heat it before sending it throughout the home. As they receive water directly from the mains, the water pressure from taps and showers will depend on water pressure from the mains. Homes with strong water pressure will therefore benefit from a strong flow of water from taps and showers.

However, homes with less than ideal water pressure will struggle to have powerful showers, especially in a large home with lots of taps. A combi boiler in a home with low water pressure may also struggle to send enough hot water when multiple taps are open.

How to increase water pressure with a combi boiler

The main disadvantage of a combi boiler is that it limits the options for increasing water pressure. Unlike conventional boiler systems, it is not possible to install a boiler pump to increase water pressure because a combi boiler must take water directly from the mains.

It is always important to make sure that the boiler is good enough to support a steady and strong flow of water throughout the home. Larger combi boilers can provide a better flow rate, so before installing a new boiler system ensure that the boiler will be able to cope with the demand for water throughout the home. Your installer should be able to recommend the most suitable solution for your heating and hot water demands.

Nevertheless, you will also be limited by the flow rate available from the mains. If your home is in an area with a low flow rate, the combi boiler will always be limited in the strength of water it can send to taps and showers.

dripping shower head

What alternatives do I have to increase my shower water pressure with a combi boiler?

One alternative option for people looking to increase the water pressure in their shower is an electric shower. Electric showers are a versatile option as they take cold water directly from the mains, bypassing the need to take water from the boiler. A heating element in the shower unit heats the water to the desired temperature, the size (kW rating) of the shower unit directly affects the available pressure or flow rate.

Due to not taking water from the boiler, electric showers carry the benefit of having a reliable flow even when multiple taps and showers are being used at the same time. The stronger the kilowatt rating of the electric shower, the stronger the flow; but only to a certain extent, as this is still reliant on the water pressure from the mains.

Can I connect a power shower to my combi boiler?

Unfortunately, power showers are incompatible with combi boilers. Power showers take their water supply from a hot water cylinder, which is an external tank only found in homes with a system or regular boiler. The power shower uses an in-built pump to increase the water pressure from the hot water cylinder, but it is not built to work with a combi boiler, which takes water directly from the mains.

Should I swap my combi boiler for a system or open vent boiler?

Combi boilers have many advantages over other boiler models. Its compact size opens up more space in the home and its efficient system of heating can help you save money in the long term. However, combi boilers are not always suitable for larger homes with greater demands for hot water. They are also reliant on strong water pressure from the mains.

System and open vent boilers, on the other hand, are compatible with power showers and can deliver stronger and more reliable showers, especially in larger homes. If you are considering changing your boiler system, speak to a qualified boiler installer to get specialist advice for your needs.


  • Combi boilers take their water directly from the mains, which means that water pressure sent to taps and showers depends on the water pressure from the mains.
  • Combi boilers are incompatible with boiler pumps, which means that power showers cannot be installed with a combi boiler system.
  • Electric showers can, however, help improve the water pressure in a shower slightly.
  • System boilers and regular boilers can be connected to power showers.

Contact your local Vaillant installer for further advice