Water pressure guide

The Complete Guide to Bathroom Water Pressure

Water pressure is a vital component of your bathroom systems, but just what is it and how does it work?

If you aren’t a professional, water pressure can be difficult to understand, particularly if you are replacing your appliances as part of a renovation or they need repairing. You need to know what type of water pressure your home uses and how it matches up with any potential shower or tap.

Plumbworld has made this complete guide to water pressure to help you understand what it is, how it’s measured, how you can increase it and the potential issues of mismatched appliances with your bathroom pressure level.

Read on to find out all about water pressure and the most important questions surrounding it…

What is water pressure?

Put simply, water pressure is a measurement of how quickly the water flows through the pipes and through your taps or shower

If your water pressure is low, water will flow slowly and take longer to fill up a sink or a bath, especially in an upstairs bathroom. If the water pressure is higher, it will fill up much quicker and your shower will be more powerful.

Tap with regular water pressure

If you have lived in a house for a while it can be difficult to know whether you have high or low pressure, as the speed with which the water comes out is what you are used to and consider “normal”.

Water pressure in the bathroom really only matters when you are thinking about upgrading or renovating your bathroom.

Water pressure is linked to your home’s boiler, along with a water tank, so it’s important to know which type of boiler you have.

What are the types of boiler?

There are three types of boiler systems - gravity-fed, combi boiler and unvented - and each has its own influence on your water pressure.

Gravity-Fed: Often found in older properties, this system will usually feature a cold water tank in the loft and a hot water cylinder elsewhere in your home. This means you will usually have a low-pressure water system. However, if you have enough height between the cold water tank and a tap or shower outlet, it may be possible to have a higher pressure.

Read more: Boiler Maintenance Tips & Checks


Combi Boiler: If you have a wall-mounted boiler that’s located in your kitchen, for example, you have a combi boiler system. You may not have a cold or hot water storage tank in the property, which means you have a high-pressure water system. Fed directly by mains pressure cold water, it is then quickly heated and pumped around your home.

Unvented: If your property has a hot water tank but no cold tank, you have an unvented water system that will provide high-pressure water. Water is often stored at the mains pressure level in a hot water tank and heated by immersion heaters attached to the side or via your central heating.

How is water pressure measured?

Water pressure is measured in bars against how far the water is needed to be pumped around a property. The base measure is that one bar of force is required to push water to a height of 10 metres.

All taps and showers are rated with a minimum required pressure rating, which will usually be between 0.1 and three bar. Anything below one bar is considered low pressure.

By law, your water supplier must be able to supply a statutory minimum of 1 bar of normal mains water pressure to your home. This can be measured where pipework enters your property - your home’s boundary, for example.

How to check your water pressure

Checking the water pressure of your home can be done in a number of ways, such as calling your water supplier or plumber.

A plumber will use a pressure gauge tool, which you can buy yourself and fix to a tap. Alternatively, you can have a rough guide by measuring the distance or drop between your water tank and the tap in metres.

Water pressure gauge

An easy way to remember is this:

One metre = 0.1 bar

Calling your supplier is also handy if you live on a hill in a gravity-fed system, as those at the top of the hill will have a lower pressure than those at the bottom.

You can check the pressure of your home using your taps and shower - the two appliances influenced by pressure. These tests are also handy if you think your appliances have seen a drop in pressure over time. See how to test your water pressure below:

How can I test my water pressure?

To test the water pressure in your taps, get yourself a water jug between one and two litres in size and a stopwatch. Put the jug under a tap, turn it on, and time six seconds. Then, turn your tap off.

Fill a jug with water

Now, the following calculation:

The amount of water in the jug in litres multiplied by 10. 

The resulting figure will be your property’s flow rate in litres per minute. If the flow rate is less than 10 litres per minute, you have low water pressure. A flow rate between 10 and 15 litres per minute is considered acceptable but can be improved. A flow rate that is above 15 litres per minute will be regarded as good.

How to test water pressure for a shower

Like testing your water pressure, you’ll need a one-litre measuring jug and a stopwatch. Place your jug under the shower and turn it on. Then, time how long it takes to fill the jug. If it takes longer than six seconds to fill the jug, your shower is running at a low water pressure.

Why is my water pressure low?

If you see a drop in water pressure for your taps or shower, it could be for a number of reasons, such as demand, pipes, blockages and old appliances.


A common one being the time of day you are using your appliances. In the morning, between 7 and 9 am, when everyone is having a shower and getting ready for work or school, pressure can be lower, so the water flowing out of a tap or shower may be lower than usual.

Narrow Pipes

Aside from incidents causing a drop in pressure, older properties have generally been built with narrower pipes than more modern homes. This can cause problems with low pressure when using your appliances or trying to run them at the same time. Pipes in modern houses can be twice as wide as older properties, so these issues are often not found in new builds.

Tap low pressure

Blocked Pipes

Like narrow pipes, the supply and water pressure to your home can be impacted by blocked pipes, either through limescale, rust or dirt. Like your drains becoming blocked and leading to sinks or toilets being slow to drain, the same can happen for water supply, causing lower pressure.

Clogged Appliances

As your pipes can be blocked, so too can your taps and shower. Limescale can build up over time which can cause a substantial drop in flow and water pressure. Many showers have a filter to protect them from pipework debris, which can become blocked, too. If your tap runs at a different rate than your shower, and vice-versa, this is likely the issue.

Read more: How to Remove Limescale from a Bathroom

Shower low pressure


Specifically for showers, they will not perform as expected unless there is a minimum height of one metre between the shower head and the water level in your property’s water tank. Called the ‘head of water’, the higher the head, the greater your water pressure and vice-versa.

Obstructed Valve

You experience low water pressure if your shut-off valve is obstructed or even closed. Usually found under your kitchen sink, the valve can become obstructed by debris. Likewise, if you’ve recently bought and moved into a new home, had building work done recently, then you should check the valve is fully open. If you think the valve is broken, call a plumber.

How to increase water pressure

There are numerous ways to increase the water pressure in your taps and shower, from cleaning to buying pumps. We’ve explained the main options below.

Cleaning Taps and Shower Heads

Cleaning a shower head

Thoroughly clean your taps, removing limescale and any dirt that may be on them or in the water outlet. Limescale can build up over time, so regular cleaning will avoid this. The same goes for your shower, which can become clogged with limescale or dirt. Remove the shower head to clean or use a bag around. Also, make sure you check the shower hose isn’t kinked or damaged.

Replace Your Shower Head

Triton Eva 1 Spray Shower Head Chrome

An alternative to cleaning, or the next step if you find a fault, is to replace the shower head. Cleaner insides, new hoses and an unclogged handset will often make a bit of difference to the water flow and pressure. You could also try an adjustable shower head to check the water flow regularly.

Fit a Shower Pump

Stuart Turner Monsoon Shower Pump 2.0 Bar Twin Impeller Positive Head

If you want a stronger flow of water and higher pressure for your shower, you can fit a water pump to your existing system. Fitted to the water system, the pump is activated when you switch the shower on with water travelling through the shower pump before coming out of the shower head. These are particularly useful for gravity-fed systems and older properties. 

Install a Power Shower

Mira Vigour Power Shower White & Chrome

Fitting a power shower will use both your hot and cold water supplies to feed the flow to the shower via an electrically driven pump within the shower’s box. Designed to with low-pressure water systems, you could see up to three times the flow. The only downside is that installation is often higher than the more cost-effective shower pump option.

Read more: What Are The Different Types of Showers?

What is the best water pressure for a tap?

If your property has low water pressure, you should consider taps that are suitable for both high and low-pressure systems. Just be sure to check that the minimum water pressure is the same as your water pressure, or even lower.

For high water pressure, choose taps that are suitable for, like above, high and low water pressure systems, or just for high-pressure only systems.

What is the best water pressure for a shower?

A low-pressure water system offers a wide choice of showers, including mixer showers, digital showers, electric and power showers. These are all suitable as long as the pressure is achieved.

Read more: What is a Digital Shower & How They Work

If you have a high-pressure system, you will have a higher flow rate and can, therefore, consider larger shower heads or rain heads, body jets and have two or more appliances running at the same time.

Read more: Electric Shower Guide for Buyers

High-pressure water systems work well with mixer, electric, or digital showers without the need to install a pump. This is because the water pressure will be strong enough already.

If you're looking for further advice on bathroom water pressure and the appliances you need, take a look at the following posts - How to Improve Water Pressure in Your Shower - Rainfall Showers and Rainfall Shower Heads - Bathroom Taps Buying Guide.

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