Yes, it is a well water system.
Water has already been shut off, I'll open all the taps, and try to plunge to remove the rest from the toilets. Will try and obtain RV antifreeze.
Thanks to all for their advice.
Oh I used to be disgusted, but now I try to be amused-E.Costello
'01 Kawasaki W650, '05 Yamaha XT225