Understanding Water Pressure and Flow

Choosing the right taps, showers and bathroom fixtures depends on understanding your home’s water pressure. Get it right and you’ll enjoy powerful showers and fast-filling baths. Get it wrong and you could end up with a disappointing trickle.

This guide explains everything you need to know about water pressure and flow, how to check what you have, and how to choose products that will work in your home.

What is Water Pressure?

Water pressure is the force that pushes water through your pipes and out of your taps. Without adequate pressure, water simply wouldn’t reach the upper floors of buildings or flow with any useful force.

Pressure is measured in bars. One bar is the force needed to push water up 10 metres. Most UK homes have water pressure somewhere between 1 and 3 bars, though this varies considerably.

Several factors affect your water pressure:

• Height and location – Homes at the top of hills often receive lower pressure than those at the bottom. Your pressure depends partly on how high your water supplier’s reservoir or tower is above your property.
• Time of day – Pressure is typically higher late at night when fewer people are using water, and lower during peak times like mornings when everyone is showering.
• Local demand – In summer, when people are filling paddling pools and watering gardens, you may notice reduced pressure.
• Your internal plumbing – Partially closed stop taps, old pipes, or poorly designed systems can all reduce the pressure reaching your taps.

What is Water Flow?

While pressure is the force of the water, flow is the volume – how much water you receive. Flow depends largely on the size of the pipe connecting your home to the mains supply.

Think of it this way: you might have good pressure, but if your pipe is too narrow, you won’t get much water through it. A single tap might work fine, but turn on a second tap or start the washing machine and you could be left with a trickle.

Older properties (pre-1970s) typically have 15mm diameter supply pipes. These were adequate when homes had fewer water-using appliances, but can struggle with modern demands – dishwashers, washing machines, power showers and multiple bathrooms all competing for water.

Newer properties usually have 25mm diameter pipes, providing much better flow for running several taps and appliances simultaneously.

If you live in a converted house, upper floors may experience flow problems as the ground floor draws most of the available water.

Pressure vs Flow: What’s the Difference?

People often confuse pressure and flow, but understanding the difference helps you diagnose problems and choose the right products.

• Good pressure, poor flow – Water comes out forcefully but the volume is low. Often caused by narrow pipes or partially blocked pipes. You’ll notice this when running multiple taps reduces flow to a trickle.
• Poor pressure, good flow – Plenty of water but it dribbles out weakly. Common in properties on hills or far from the water tower. A pump can help.
• Poor pressure and poor flow – The worst combination. May need both plumbing improvements and a pump.

How to Check Your Water Pressure

Before buying taps or showers, it’s worth checking your water pressure. There are several ways to do this:

Method 1: Use a pressure gauge

The most accurate method. You can buy a simple pressure gauge that attaches to an outside tap or washing machine connection. Turn off all other taps and appliances, attach the gauge, and turn on the tap fully. The gauge will show your pressure in bars.

Method 2: Ask your water supplier

Your water company can tell you the pressure in your area. Contact them or check their website – many have online tools where you enter your postcode.

Method 3: The bucket test (for flow)

Place a bucket under your bath tap and time how long it takes to fill. A standard 10-litre bucket should fill in about 30-45 seconds with good flow. Much longer than this suggests low flow.

Method 4: Check your existing fixtures

If your current shower is weak despite being a good quality unit, or your bath takes a very long time to fill, you likely have pressure or flow issues.

What Pressure Do You Need?

Different bathroom products require different minimum pressures to work properly. Here’s a general guide:

Low pressure (0.1 – 0.5 bar)

Some taps and showers are specifically designed for low-pressure systems. These are ideal for gravity-fed systems (with a tank in the loft) or properties with naturally low mains pressure. Look for products marked as suitable for low pressure or with a minimum pressure rating of 0.1 or 0.2 bar.

Medium pressure (0.5 – 1.0 bar)

Many standard taps and mixer showers work well at this pressure range. Most UK homes fall into this category.

High pressure (1.0 bar and above)

If you’re lucky enough to have high pressure, you can choose from the widest range of products, including rain showers and multi-jet shower systems that need strong pressure to perform well.

Tip: Always check the minimum pressure requirement on any tap or shower before buying. On our website, you can filter products by pressure rating to find fixtures that will work with your system.

Types of Water System

Understanding your water system helps you choose compatible products:

Gravity-fed system

Water is stored in a cold tank in the loft and flows down to taps by gravity. Pressure depends on the height between the tank and the tap – typically 0.1 to 0.3 bar. Common in older UK homes. Usually needs low-pressure compatible fixtures or a pump.

Combi boiler system

Water comes directly from the mains with no storage tank. Usually provides good pressure (1-3 bar) but flow can be limited as the boiler heats water on demand. Good for most standard taps and showers.

Unvented system

Mains water is stored in a pressurised cylinder. Typically provides excellent pressure and flow. Compatible with almost any bathroom fixture.

Pumped system

A gravity-fed system with a pump added to boost pressure. Can provide excellent performance if properly installed.

Solutions for Low Pressure

If you have low water pressure, don’t worry – there are several solutions:

1. Check your stop tap

Make sure your main stop tap is fully open. A partially closed stop tap is a surprisingly common cause of low pressure. The stop tap is usually under the kitchen sink or where the mains pipe enters your property.

2. Choose low-pressure products

Many taps and showers are designed specifically for low-pressure systems. We stock a range of products suitable for pressures as low as 0.1 bar. Use our pressure rating filter to find compatible products.

3. Install a shower pump

A pump can dramatically improve pressure for showers. Single pumps boost either hot or cold water; twin pumps boost both. We stock a range of shower pumps suitable for different systems.

4. Consider a pressurised system

If you’re renovating, upgrading from a gravity-fed system to an unvented pressurised cylinder can transform your water pressure throughout the house. This is a bigger job requiring a qualified plumber.

5. Check for blockages

Old pipes can become partially blocked with limescale or debris. A plumber can check for restrictions and clean or replace problem sections.

Common Questions

Will a bigger shower head give me better pressure?

No – actually the opposite. A larger shower head spreads the water over a bigger area, so each jet is weaker. If you have low pressure, choose a smaller shower head or one designed for low-pressure systems.

Can I use a power shower with a combi boiler?

No. Power showers have a built-in pump designed for gravity-fed systems only. Using one with a combi boiler can damage the boiler. If you have a combi and want more pressure, check your mains pressure first – it may already be adequate for a good electric or mixer shower.

Why is my new tap weaker than my old one?

Modern taps often have flow restrictors or aerators to save water. These are good for the environment but can feel weak on low-pressure systems. Some restrictors can be removed – check the tap instructions.

Is 1 bar enough for a good shower?

Yes, 1 bar is adequate for most mixer showers and many rain showers. You’ll have a comfortable showering experience. Below 0.5 bar you’ll want to look specifically at low-pressure models or consider a pump.

Need Help?

If you’re unsure about your water pressure or which products will work in your home, we’re happy to help. Contact us at support@bathroomessence.co.uk with details of your system and what you’re looking to buy, and we’ll point you in the right direction.

You can also visit our Birmingham showroom to see products in person and discuss your requirements with our team.