SCH is probably right about the low point drains. Get them shut. They are probably inside.
You are not very clear about the others, but it sounds like you have two each two position valves so there is not an "ON" and "OFF". One valve selects to fill your tank from the city connection or the tank to the pump suction (in), and the other selects your system source as from the pump or the city water connection.
Matt
Matt & Mary Colie
A sailor, his bride and their black dogs (one dear dog is waiting for us at the bridge) going to see some dry places that have Geocaches in a coach made the year we married.