Water pressure is a measure of the force that gets the water through our mains and into your pipes.

It is measured in 'bars' - one bar is the force needed to raise water to a height of 10 metres.

We need pressure to push water through our pipes and into homes and businesses, whether they are in valleys, higher and hillier areas, or are raised like some flats and apartments.

The amount of pressure at your tap depends on how high our service reservoir or water tower is above your home, or on how much water is being used by other customers.

Water pressure can vary at different times of the day. Pressure is normally higher late at night when very little water is being taken from our network and most people's taps are closed.

In the morning when people are taking a bath or shower, or watering their garden on a hot evening, there is a bigger demand for water which can cause low pressure.

The pressure also varies with the ground level. In hilly areas, the pressure will usually be high in the valleys, which are a long way below our reservoirs, and lower on the hilltops.

We have always undertaken small-scale local network modifications to resolve pressure issues, manage leakage, and respond to operational events. Since 1995 such activity has been playing an increasing role in the management of leakage.

In most cases the work was completed without an impact on customers. Network changes were reversed in the event of evidence of customer problems.

Since 2002 more strategic reconfigurations of large pressure zones have been undertaken, particularly in London.

These zones are hydraulically connected parts of the network in which the low-lying areas are operated at a significantly higher pressure than is desirable (or often needed) in order that the areas in higher ground are adequately pressurised to meet statutory and customer service requirements.

As the work has expanded a communications strategy has been developed to meet all London Boroughs in the areas of the project work.

We continue to hold individual customer meetings with all owners of tall buildings highlighted through an extensive and detailed survey process.

Customers can make changes to their internal plumbing to increase their water pressure - for example by ensuring their stop tap is fully open, or checking that any systems that depend on the pressure of water reaching the property are set to the statutory minimum level of 1 bar/10 metres head.