Low pressure fix

Have a rurual property with a large house. Water pressure seems to vary greatly within the home. Double sink upstairs one faucet has half the water pressure as the one next to it. Shower in the same bathroom and tub faucet also very low pressure. Sink in kitchen has its own small water heater and good pressure. Shower on main floor has good water presssure as long the washing machine insnt running. Water is supplied to at least a half dozen houses from a spring 500 meters away. What is the solution for this?