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Shower pump installation

running shower - shower pump

You can spend thousands renovating a bathroom; there are so many different luxurious touches possible; wet room, roll-top bath, underfloor heating. In California, people even have coffee machines and fridges in their bathrooms. But forget the bells and whistles; there’s nothing quite as luxurious as a properly powerful shower.

For us, this means having the water pressure of an invigorating torrent, rather than the drip-drip dribble of a leaky tap. If you’ve had a luxury shower installed but been let down by your shower water pressure, you’ll need to install a shower pump. In this guide we’ll show you how to choose one for your specific hot water system, and how to tackle shower pump installation so that you’re enjoying a Niagara Falls-like experience in no time.

Table of contents

  1. What does a shower pump do?
  2. What is head pressure?
  3. How does a shower pump work?
  4. Do I need a shower pump?
  5. Do I have a gravity-fed system?
  6. Do you have a positive or negative head system?
  7. How much pressure is ideal for your shower pump?
  8. How to install a shower pump
  9. FAQs

What does a shower pump do?

A shower pump boosts the pressure of your hot water system. If you’re renovating or making home improvements or have a buy-to-let property and you want your tenants to have a decent shower experience, you’d typically add a shower pump into a hot water system where the ‘head pressure’ isn’t enough to create a decent shower experience.

What is head pressure?

‘Head pressure’ is a specific measurement of pressure used in pump systems. Generally speaking, it’s a measurement of the height difference between the water being moved and the ‘discharge point’ or source. In the case of your shower, that means the height difference between your cold water tank (or wherever your water comes from) and your shower head.

How does a shower pump work?

A shower pump is quite a small unit (about 30cm x 30cm x 30cm) that you can install to boost the volume of water and therefore the head pressure in the pipes between the hot water tank and the shower unit.

Do I need a shower pump?

If you know your water pressure could be better at the shower head (and it’s sufficient elsewhere), then a shower pump will help you significantly improve your morning wake-up routine.

If you have other problems with your plumbing that could be causing lower water pressure in general, do get them checked out asap, especially if you suspect you may have a leak. Read our article on common water leaks in the home and how to fix them. There are several checks you can do to detect a water leak if it is not obvious.

Check your water flow rate

Even if you don’t already have a shower, you can see how quickly it takes to fill your bath. Read our article on how to test water pressure with our simple test. Anything between 10 and 15 litres per minute is the ideal amount of water pressure.

If your water flow rate is less than 10 litres per minute, your home could really benefit from a shower pump.

Now identify your hot water system

In order to choose a shower pump, you must know what kind of hot water system you have in your home.

Do I have a combi boiler?

If you have a combi boiler, unfortunately you won’t be able to install a shower pump because it only works in conjunction with an open-vented / stored hot and cold water system. The benefit of a combi boiler is that it’s able to provide both hot water on demand and central heating without the need for a water tank or cylinder. But if your mains pressure is frustratingly low, this means putting up with terrible showers. If an invigorating shower is super-important to you, changing your boiler to a conventional or system boiler will solve your issue.

Do I have a gravity-fed system?

A gravity-fed hot water system is normally found in older properties, and relies on the general mains water pressure to your home and also on the head pressure. Older properties do tend to suffer from problems with low water pressure.

Do you have a positive or negative head system?

If you know you have a gravity-fed system, you can then work out if you have a ‘positive head’ or ‘negative head’ system.

Positive head = positive shower pump

A positive head system is the most common system, and it’s ideal because in these systems the cold water tank is positioned 60cm higher than the shower, so gravity allows water to flow downwards and that way you naturally get the 0.6 litres per minute flow that a positive shower pump needs to get its impellers going (they do the actual pumping).

Negative head = negative shower pump

Negative shower pumps are used in single-storey properties like bungalows or flats where there’s not enough distance between the cold water tank and the pump. In these types of installations, you should choose a negative shower pump. Negative shower pumps don’t benefit from gravity at all; they work by sucking up water from the cold water tank and feeding it to the pump’s impellers. You install it so that it’s level with the cold water tank or even above it.


Another thing you can customise to your needs is the number of impellers required. An impeller is the actual pump part; a rotor that increases the pressure and flow of water through the pump and down the hose to your shower head. You can buy shower pumps that are fitted with either single or twin impellers.

Single impeller pump

If you choose a single impeller it will boost only the hot water in the pump. The cold water will come in using your home’s normal cold water pressure, so this will need to be adequate to match the boosted hot water supply.

If the cold and hot water tanks are far apart in your household, a single impeller pump will usually be needed for both sides – the hot and the cold.

Twin impeller pump

The twin impeller pump is the Rolls Royce of the shower pump fleet. It boosts the flow of both hot and cold and is mostly used on positive head systems. It delivers an even amount of pressure and lets you control the mix of hot and cold water – so it’ll be easier to hit that sweet spot temperature you like.

Regenerative and centrifugal shower pumps

Another decision to make is whether you want a regenerative or centrifugal pump.

Regenerative pump

Regenerative pumps (sometimes also known as peripheral or turbine pumps), are the noisier and therefore cheaper option. They have a water wheel impeller inside the end of the pump. Water goes in through the inlet, and spins around a wheel inside the pump and builds pressure. A stripping block ‘strips’ the water from the impeller and out through the outlet.


  • Cheaper
  • More robust and less susceptible to damage from aeration


  • Noisy (because of the stripping action)

Centrifugal pump

Centrifugal pumps use centrifugal force (outward force on a mass when it’s rotated) to increase water pressure within the pump. Water enters through the inlet and spins round in the impeller chamber. Water is thrown outwards using centrifugal force, building up higher pressure inside which then forces the water out of the pump.


  • Higher flow efficiency
  • Quieter
  • Multiple impellers can be added to increase pressure (‘Multistage impeller’)


  • More expensive
  • Needs a flange installing to protect from aeration damage

How much pressure is ideal for your shower pump?

Now that you’ve worked out which type of shower pump you need, you’ll need to pick a pressure rating:

  • 1 bar shower pump – perfect for small shower heads
  • 1.5 bar shower pump – good for a standard shower that just needs a little more pressure
  • 2 bar shower pump – just a little more pressure than a 1.5, great for a normal shower set-up
  • 2.5 bar shower pumps – perfect for a larger-than-average shower head or if you want a power shower
  • 3 bar shower pumps – the big kahuna – ideal for power showers, larger shower heads and/or showers with body jets

How to install a shower pump

It’s important to read and follow the instructions that come with your shower pump to the letter. Use the following information as a general guide.

Tools you’ll need:

  • Towels
  • Bucket
  • Adjustable spanner
  • Screwdriver
  • Electrical tester

Step 1
Work out where to place the shower pump. It needs to be:

  • An easy-to-access spot to make maintenance and cleaning easy
  • Uncovered to stop the motor from overheating
  • At least 2 feet or 600mm away from the shower tray or basin
  • An ideal place is a loft, airing cupboards or under the bath

Step 2
Top tip for avoiding a noisy shower pump:

  • Don’t screw the shower pump into the floor

Step 3
Once you’ve chosen where to install your shower pump, you can connect the electrics. If you’re experienced with electricity, you will want to connect it to the house’s electrical supply using a 230v switched spur off a ring main. If you don’t have any experience with electricity, or don’t feel you can do this completely safely, don’t attempt this work; call a professional to do it. Don’t take risks with electricity as it can be dangerous.

If you can do the above confidently, using all the correct electrical safety and testing procedures, just remember not to connect your shower pump to the electricity supply for your hot water cylinder heater or anything else that needs a dedicated supply of energy.

Step 4
Create a local isolation valve so that you can isolate the water supply to and from the pump. You can do this by fitting a 22mm full bore isolating valve onto the cold-water supply pump.

Step 5
Now you need to seal the pump and prevent air ventilation (which can damage centrifugal pumps the most). Fit a Surrey flange to the top of the hot water cylinder for 15mm connections and use an Essex flange for 22mm connections.

Step 6
Use flexible hoses to link to the incoming and outgoing delivery pipes to prevent damage to the pump – it also reduces noise.

Step 7
Fully flush the pipework before connecting it to the pump to avoid any debris getting in and damaging it.

Step 8
Find out how regularly you need to clean and maintain the unit and put it in your diary so you keep it clean and well-maintained, always.

Enjoy your new and improved shower!
We hope you’ll soon be springing out of bed for your invigorating morning shower. If you need any help with if you need any help with unexpected plumbing issues our Plumbing and Drainage cover is available – plus you can count on our emergency repair team to fix any problems as soon as is practically possible.


Where should a shower pump be located?

A shower pump needs to be:

  • Suited to your type of hot water system and head pressure (see guide)
  • An easy-to-access spot to make maintenance and cleaning easy
  • Uncovered to stop the motor from overheating
  • At least 2 feet or 600mm away from the shower tray or basin

An ideal place is a loft, airing cupboard, under the bath, or above the water cylinder

Are shower pumps easy to install?

You will need to be a moderately gifted DIY-er with experience in plumbing and correct electrical safety experience. This project isn’t for beginners.

What shower pump do I need?

It depends what kind of property and hot water system you’re installing it in. Find out:
1. What kind of boiler you have (combi boilers aren’t compatible)
2. What kind of hot water system you have
3. How much head pressure you have
4. How much extra pressure you need
And then come back to this guide to find out whether you need a positive or negative pressure pump, and whether you’d prefer a centrifugal or regenerative pump.

What is the quietest shower pump?

A centrifugal shower pump is the quietest (but not the cheapest). Remember to sit the shower pump on a 50mm thick concrete block and never screw the shower pump into the floor to keep the noise down.

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