I recently read something (cant find the link, sorry) about having a generator and pump on-site, and then pumping water from your swimming pool to your sprinklers. I suppose not everyone has a pool, but collecting rainwater etc in an underground sump could be sufficient.
You could even imagine a closed-system that collects rain/sprinkler water from the roof guttering and drains around the property and channelling them into the pool/sump. You'd lose a lot of water to evaporation/steam in a fire I guess, but it could buy you some time.
The other alternative I guess is just dont build your house out of combustible materials. I guess some stuff might just melt in hot-enough conditions, but by that stage where ceramics and metals are just melting in ambient temperatures I think its pretty much a game-over situation regardless... but before that extreme you can probably get a lot of mileabe by building your houses out of brick (there seems to be a lot of brick foundations left in the footage I am seeing on TV)