Why is the water pressure so high from my overhead water tank?
You may need an aerator.  If it needs replacing, then the water may spatter a lot.  The aerator is the piece that screws into the end of the spigot.  It limits the flow of water to between 1.5 and 2.5 gallons per minute and entrains air into the water stream to prevent splashing.  From what you describe, it may even be missing.  You can pick one up at any hardware store.