We actually run 2 head tanks, 1 inside, 1 outside. The outside tank we pump all our raw sap into. Inside we have it set up by just flipping a few valves we can run that raw right into the evaporator, or into the RO then up into the inside head tank and run off that. Once we are done RO'ing raw sap, another flip of a valve and we can RO the head tank.