turbulent flow of water

Turbulent flow occurs in pipes when the http://en.wikipedia.org/wiki/Reynolds_Number exceeds about 2300. For water at ambient temperature in a 1" diameter pipe, the velocity for this criterion is quite low and the chances are that the flow is already turbulent if the pipe has been correctly sized.

In general terms, velocities of 1.5m/s are common in pipes, and if the velocity exceeds 3m/s then it is time to consider increasing the pipe size to bring the velocity down.

The absolute pressure and the supply pressure are not particularly relevant.

The pressure drop along the pipe can be calculated from the http://en.wikipedia.org/wiki/Darcy-Weisbach_equation, making due allowance for bends and other fittings.