If you are under the IPC, the 2006 code says you can use PEX for water service pipe or from the meter to the point of distribution. I don't know how many GPM you are thinking about but I think the size for PEX may be limited to 2" or so max. Why not PVC for Service water pipe (note cold water)? For 3000' you better be sure you have good water pressure to start with and figure any elevation head you have plus friction loss to size it.