When I deal periodically with weather/flood issues here, @Jim472 , I find the best thing is to immediately make the guests part of the process. Send them the article link, talk about your experiences with these outages. See if you can work out with them how many buckets they will need, how much drinking water, etc.
I feel for you, having to deal with this. Feeling for them, too. High stress time, writing exams, and no water.
Will you let us know what you end up doing, and how (hopefully!) wonderful they are about it?