I had to have my mains water switched off for an extended period recently and I was quite staggered by how difficult that was to cope with. (I didn't have any opportunity to fill bath/buckets
I coped with any loss of power to the house much more easily than not having working toilets, for example. (And they soon were because I kept forgetting not to flush them - if this happens again, I'm going to go round, in the short term, and quickly put masking tape on handles.)
How does everyone else prepare for loss of water?