The minimum @ a faucet running full should be 8 PSI and a Maximum of 85 PSI
Or depending on local codes of the water department and department of buildings.
The “BEST SINGLE reading ” is the one that does not exceed the velocity of the piping material installed to cause erosion or hydraulic shock waves from quick closing and also meets the K factor requirements for a fire suppression system for the highest located fixture and or sprinkler head. The BEST Single flow is also designed with a peek demand in fixture units and developed length taken into consideration with modern flow restrictors.
Here is an article that may help you in your quest of Pressure / volume
http://www.masterplumbers.com/plumbing/plumbviews/watersupply.