Water companies are required to supply water at a pressure that will allow water to reach to the top storey of most homes. Although, there are some exceptions to this.
This is measured at the point where the water leaves the water suppliers pipework and enters yours (usually the outside stop valve or property boundary).
As a guide, if you have a suitable single service pipe, the first tap in the home (this is usually the kitchen tap) should be able to fill a 4.5 litre (one gallon) bucket in 30 seconds, with all other taps and appliances turned off. Another way of putting it is enough water pressure to fill a cold water storage cistern in the roof space of a two storey house.
Most water companies will aim to provide at least 10 metres head (approximately 14 psi or 1.0 bar) at the end of their communication pipes. They are committed to a guaranteed standard of service to provide a minimum of 7 metres static head (0.7 bar). You can find more information about this by contacting your local water company or visiting Ofwat’s website www.ofwat.gov.uk