We have a statutory requirement to supply water by gravity continuously for domestic purposes at a pressure that will; ‘reach the top of the top-most storey of every building’ (Water Industry Act 1991 Section 65)

We also have service standards which are agreed with Ofwat that require a minimum supply pressure of 7 metres head (approximately 10 psi or 0.7 bar) , measured at the point where our communication pipe joins your supply pipe. You should be able to fill a 2 litre bottle in less than approximately 13 seconds.  

We try to improve on this and provide at least 10 metres head (approximately 14 psi or 1.0 bar) at the end of our communication pipes.

There is no legal requirement for a maximum supply pressure. If you find that the supply pressure exceeds the maximum working pressure of internal fittings, you may want to discuss with an approved plumber about installing a pressure reducing valve. Approved plumbers can be found through WaterSafe or on the Water Industry Approved Plumber Scheme WIAPS.

There's more information here on:

Low pressure

High pressure