Water pressure can easily be measured using a relatively inexpensive water pressure test gauge which costs approximately £10 http://fave.co/1IPpqKm
You might want to know how much pressure you have, if you are fitting a new appliance etc.
High water pressure can cause problems and may involve installing a pressure reducing valve (PRV) in order to reduce the pressure. High water pressure can cause water hammer and that can lead to leaking joints etc.
How to measure water flow can be found here- https://www.youtube.com/watch?v=j3hRYXzyV-8