There are few things in life as important as having a good quality shower installed in your home. It’s the place you start each morning and a positive day will always start with a refreshing shower.

But if your shower is lacking the required pressure, then you will always be starting the day on the wrong foot.

Fortunately, improving the water flow in your shower is quite straightforward.

In most cases, low water pressure in the shower can easily be fixed by installing a shower pump - a sort of small mechanical tool that can easily be installed on to your home’s plumbing system.

Now, if you’re new to the plumbing, this is where things can get a little complicated.

No doubt you’re wondering:

"Can I install a shower pump on my boiler?"... "What's the difference between a positive or negative shower pump?" ... "Why size shower pump do I need?"

All questions that are likely to overwhelm someone new to the pumping world.

That’s why we’ve created this guide to buying a shower pump. Taking you through the six important questions you need to answer before buying a shower pump, this guide will have your shower at full pressure in no time.

Do you have a gravity fed, combi-boiler or unvented heating system?

The first thing you need to check is what kind of boiler you have in your home.

Your choice of shower pump will depend on whether you have a:

Conventional Gravity Fed System
A gravity fed system will consist of a large cold water storage tank in the roof or loft and a hot water cylinder in an airing cupboard.

Combi Boiler System
A combi boiler is usually located in the garage or downstairs airing cupboard. Combi boilers take water directly from the mains supply to deliver water around your home.

Unvented System
In an unvented system, there is no cold water tank. Instead, you will have a separate hot water cylinder to store hot water at mains pressure. An unvented system can be located in pretty much any area of your home.

If you have a combi-boiler, you will not be able to fit a shower pump.

Combi-boilers are sealed, and a shower pump would cause a change in pressure that could potentially cause the boiler to implode.

If you are suffering pressure problems with a combi-boiler, you may need to replace your combi-boiler system or contact your boiler provider.

What shower type do you have installed?

The second thing you will need to check is the type of shower you have installed. In the UK there are three main types of shower. The manual mixer shower, the thermostatic mixer shower and the electric shower.

Manual Mixer Shower
The manual mixer shower does exactly what it says on the tin. You manually adjust the levels of hot and cold water to your required pressure and temperature. In most cases, you will need a twin impeller system to boost pressure of both hot and cold water supply.

Thermostatic Mixer Shower
Similar to a manual mixer shower, a thermostatic mixer shower is fed by both a hot and cold water supply. The thermostatic valve monitors the water and keeps the water at your desired temperature. In most cases, you will need a twin impeller system to boost pressure of both hot and cold water supply.

Electric Shower
Electric showers are a tad different to mixer showers as they only take water from the cold supply. With a heating unit built within the electric shower, they can heat the cold water to your desired temperature. As they are completely disconnected from the hot water supply, you will likely need a single impeller pump. The common model chosen by plumbers is the universal shower mate - model 46534.

If you are purchasing a shower pump for an electric or power shower, we advise that you contact your shower provider or manufacturer for further information. Each shower is built to a different specification and may need a universal pump even if they follow each of the rules in this article.

Do you need a positive or negative head (universal) shower pump?

You will need a positive head shower pump if the bathroom and showers are on floors below the water tank - that is, your cold water tank is in the attic or if the cold water tank is above the shower head if you live in a single-storey flat or bungalow.

A positive head pump needs a flow rate of at least 0.6 litres a minute and relies on gravity to start the impellers to pump hot and cold water.

Negative head pumps work by pressuring water from the tank to the shower and is the best choice for when the shower head is at the same level or higher than the water tank. This can be used in loft conversions, for example.

For more information on positive or negative head shower pumps, please read our dedicated Do I Need a Positive or Negative Shower Pump guide.

Do you need a single or twin impeller shower pump?

After you’ve decided on a positive or negative head pump, you will need to decide between a single or twin impeller system.

A single impeller shower pump is designed to pump only one type of water. This is usually only used in a water system where one of either the hot or cold water is suffering from low water pressure.

A twin impeller shower pump is designed to increase the pressure of both hot and cold water supplies. This is to ensure that both supplies are boosted to the same level. Twin impeller pumps are more common than single impeller pumps and generally lead to a higher quality shower.

graphic showing the difference between a single and twin impeller shower pump

What pipesize do you have installed?

You will also need to take into account the size of the pipes that you plan to attach to your pump.

Standard pipesize in the UK is 22mm, but it’s possible for older houses to have a 15mm pipesize.

If you have an older plumbing system installed, double check your pipesizes as only a small selection of pumps cater for 15mm pipes. A 15mm pipe should not be connected to a pump designed for 22mm pipes.

If you are reading this article in the Republic of Ireland, things can get a little more complicated as your standard pipesize is 21mm, but you can also have the 15mm and 22mm options installed in your home.

What size shower pump do you need?

The size of pump you need will be determined by the pressure requirements of your home.


  • How much pressure is needed to drive water to the taps and showers?
  • How many water units will be in use at one time?
  • Do I have more than one shower?
  • How big is my home?

Think carefully about the questions above before purchasing a shower pump. It may seem like a good idea to purchase a cheaper, low-pressure shower pump, but if you have a large family then it may fail to increase the water pressure in your shower.

Saying that we have a few general rules that should help you make a purchase decision.

A small flat

If you’re living in a small flat, apartment or house as a bachelor/bachelorette or with one partner, then you will need to purchase a pump with 1.5 to 2.0 bars worth of pressure.

Search for a 1.5 bar to 2.0 bar shower pump here.

Small family (2 Bedroom House)

For a young family in a small, 2 bedroom house, we suggest purchasing something with around 2.0 to 3.0 bars of pressure.

Search for a 2.0 bar to 3.0 bar shower pump here.

A family of four (3 Bedroom House)

If you have a family of four people plus, then we suggest purchasing a pump with about 3.0 bars of pressure.

Search for a 3.0 bar shower pump here.

Multiple showers

If you have multiple showers and taps in use at one time, then we suggest purchasing a pump with over 3.0 bars of pressure. Something like 3.6 bar should provide enough power.

Search for a 3.6 bar shower pump here.

graphic showing the different shower pump needed for different showers

Tips before choosing a shower pump

Shower pumps can be complicated tools, and each home will create an exception to the rule. If you’re bypassing a plumber it's important that you know the following pieces of information before choosing a shower pump.

Do not connect a shower pump to the mains water supply

Under British regulations, you cannot connect a shower pump to the main water supply. A shower pump must be connected to a system that is gravity fed. This is where the water is fed to the pump via a tank or cistern. These are often located in the attic of a house.
You can always install a break tank that would put a pressureless tank between your mains supply and the shower pump.

Alternatively, the flomate range by Stuart Turner combines both a pump and break tank in one kit.

Do not connect a shower pump to a combi boiler

A combi boiler is fed directly from the mains water supply and not a water tank. Combi-boilers are already working at their maximum output, so if you’re still having issues then you may need to buy a new combi boiler or contact your boiler provider.

Consider your water tank size before buying a high-performance shower pump

It’s important to check the capacity of your home’s water system. If you have a small hot water tank, then you definitely want to avoid a high-performance shower pump. A 3 bar or 4 bar pump will feel fantastic but your shower will literally last 2 minutes.

Choose a quiet location

Pump location can make a huge difference when it comes to pumping satisfaction. Choose a quiet and level location for the pump, as even the most expensive pumps will vibrate and make a noise when operating. Consider purchasing a polystyrene pad or a specially designed noise reduction mat to dampen out any noise.

Help and Advice

If you’re struggling for advice, ring our dedicated pump experts for free advice on: 0800 112 3134 or 0333 577 3134.

We’re open Monday to Friday 07:00 - 17:30 and Saturday 08:30 - 12:30.