Understanding Your Water System

There are a number of water systems in houses around the UK with varied pressures for both hot and cold water supplies.

Gravity Fed Systems

These have a water tank, usually in the loft and the pressure can vary depending on the distance in height between the water tank (source) and the water outlet (such as the shower or tap).

For example, if the height is 1 metre then the water pressure is 0.1 bar; similarly, if the height is 3 metres then the water pressure is 0.3 bar. Very few homes will have a greater water pressure than this if they are gravity fed.

Gravity Fed Hot Water

These have a water tank in the loft feeding a hot water cylinder which then feeds the rest of the house. Cold water comes directly off the mains. This means the hot water comes from a cylinder that’s fed by a cold water tank in the loft.

However the cold water comes directly from the mains supply and therefore should have a much higher water pressure. Mains water can be anything from 3 bar to 8 bar, depending on the altitude of the house compared to the local water reservoir or water tower.

In this case, the pressure imbalance can cause problems with thermostatic shower systems and we would recommend using a pressure reducing valve for the cold water feed.

Gravity Fed with Water Pump

These systems have an increased flow of water but not necessarily increased pressure. Pressure only increases with a restriction of the flow, so if the flow has been increased the pressure will decrease.

Water Systems – Direct Vs. Indirect

It can be handy to know how water enters and exits your property and the route it takes within your home. There will be similarities in the layout of your plumbing, no matter which part of the country you live in.

This guide covers the basics and helps you understand the ins and outs of direct and indirect systems. The water supplied to your house by the local water company arrives at a stopcock at the property boundary.

The supplier owns the route the water takes to your house, including the stopcock and the surrounding area. Any problems faced here will be fixed by the company.

This should be factored in when designing your garden and any land that would need to be dug up for repairs should be easily replaceable without ruining the wider area.

Any problems regarding your property will be the responsibility of the homeowner or landlord. There are two common types of water systems: indirect water systems and direct water systems.

Indirect Systems

In short, an indirect system is a mains-fed system, which initially supplies the drinking water to one outlet and then travels to a water tank in the loft feeding all other water outlets.

The advantages of an indirect system include:

• Less noise due to lower pressure
• Less risk of wear and tear on taps and valves
• Pre-heated water is held in an insulated tank, which is useful if the mains are cut off and a reserve of water is needed.
• This is also great for large households where hot water is used at the same time.

The disadvantages include:

• Higher risk of frost damage in the winter as the water needs to be pre-heated for usage.
• More pipework is needed, which may ramp up the initial installation cost.

Direct Systems

Direct systems do not store water and supply fresh water to every outlet. They are often found in houses that have a combi-boiler, as these negate the necessity of a water storage tank.
In summary, a direct system:

• Delivers cold water to every available tap outlet, meaning drinking water is available in all locations.
• Is cheaper to install and there is less risk of damage due to a smaller amount of pipework.

The disadvantages are:

• More noise due to higher pressure
• More risk of wear and tear on taps and valves
• No reserve water if the mains are cut off.

Take a look at the infographic below to find out more about the differing types of gravity fed water systems that exist and which ones are more suited to particular types of household needs.

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