If you want to install new plumbing fixtures in your home, you need to know what type of water pressure system is in your home.

Knowing more about the water pressures system in your home will help you select fixtures and fittings that provide a great match. Choosing complementary pieces of equipment helps you get the performance you want and avoid disappointment. The more you know about your water pressure system, the better.

In general, there are three varieties: gravity-fed, combi boiler, and unvented systems


This is the most common system in older properties, gravity-fed water pressure systems rely on the magic of gravity to deliver water to faucets and other water outlets around your home under high pressure.

In gravity-fed systems, a cold water tank sits high up in the property somewhere. A pump hauls water up the roof from the mains supply, and then the tank releases water through outlets in its base.

Gravity fed systems provide water to the hot water tank as well as cold taps in your home and appliances that use cold water, like the dishwasher or washing machine.

In general, you gain about 1 bar of pressure for every metre of elevation. So if you want five bars of pressure for the water coming out of your kitchen tap, it needs to be five metres below the water tank.

Combi Boiler System

While gravity-fed water pressure systems are commonplace in older homes, the combi boiler system is the most frequently seen option in newer builds. You find this type of boiler most often in small apartments and new homes. The small size of the system helps to free up space for other things and cut costs for the developer.

Most combi boilers do not provide any pressure themselves. Instead, they rely on mains pressure to deliver both hot and cold water to your home. Combi boilers direct water into their interior, apply heat, and then deliver it, on-demand whenever you turn on the hot tap.

As you might imagine, heating cold water as it comes in from the mains requires a lot of energy. Combi boilers, therefore, work in a similar way to power showers. They pass water over hot elements that heat it rapidly before it leaves the unit and travels to any appliance it is connected to in your home.

Combi boilers can be more efficient than traditional gravity-fed systems with a hot water tank. Unlike in the gravity-fed system, you don’t have to keep a hot water tank permanently hot, just in case somebody devices that they want to run a bath – you only heat hot water that you need.

The combi system also offers another benefit: as unlike traditional gravity-fed system. Water comes in under mains pressure and, for the most part, is identical throughout the home, whether you need water on the ground or first floor. so long as the mains pressure remains consistent.

Combi boilers deliver moderate pressure. Most can provide one or two bar.

Unvented Systems

Unvented water systems deliver hot water at mains pressure. The system relies on a special hot water tank which collects water, heats it with elements, while at the same time, pressurising it so that it comes out fast.

If you have a tank for hot water but not for cold, then the likelihood is that you have an unvented system. Unlike a combi system, you have a permanent store of hot water. And, unlike a gravity system, cold water comes directly from the mains.

A Water booster pump can be fitting to increase the water pressure in your home, leaving you with more of a variety to choose from when purchasing appliances for your home.


A water booster pump provides pressure to move water from a storage tank to your tap, shower head or throughout a whole house or commercial facility. Low water pressure can make simple tasks a hassle, but a booster pump may be the perfect solution.  Sometimes, however, plumbing problems may be the cause. Before buying a water pressure booster, have your plumber check the pipes as they may be clogged, or the pressure reducing valve may need adjusting.

There are two kinds of pumps: positive and negative.

Positive pumps work to increase water pressure in gravity-fed systems. They sit under the cold-water tank and push out incoming water faster.

Negative pumps do not need situating under gravity flow to function. You can, therefore, use them at shower level or in a loft conversion.

If you want a pump to boost flow to a single outlet, you will need a one-bar rated pump. For an entire floor, you will need a two-bar. And for a large home, you will want a three-bar, especially if you are using large showerheads.

Pumps always work better pushing rather than pulling, so put them on the floor next to your hot water tank if you have one.

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