Waterborne disease in the floodwater is possible leading to diarrhea and dehydration and you can't drink money...preparation (or even aid in some cases) is needed:
Failing that (logistics over the Black Friday and Cyber Monday sale period are going to be hamstrung), washed and ex-food grade IBCs with steam-activated unmilled biochar. But, where are the supplies? Maybe in the future? There are also other 'Activated Carbon' water filters on the market but will there be enough of them and can they get to the flooded regions in time?
Boiling water in a billy could work too if one can get to dry land fast enough...
But, hopefully most people will evacuate fast enough and have somewhere to stay with food and water. For those people that stay to defend their home, good luck! In this scenario, a generator might be needed too.
Purchasing a solar generator will be far more useful and standalone than a diesel generator that depends on a diesel supply chain that could be interrupted. For eg.,
The above solar generators use a LiFePO4 battery chemistry for more charge cycles and better chemical and thermal stability compared to a pure Li ion battery chemistry (rookie mistake).