^^^ I am not so sure about this. Several summers ago wild fires in B.C. threatened the Sun Peaks Village (fire got within a couple miles away) so they used the snow guns to hose down the hotels in the village core. Shortly afterwards they changed the plumbing so they could divert water from the snow making reservoir to the village fire hydrants.
The reservoir is located in the alpine, 2500' (est.) above the village so it is a gravity fed low pressure system with no pumps other than whats on the snow guns. This might make the fire hydrant switch over more viable with no toilets ever harmed.