Good, this should have always been the norm. You literally cannot predict disaster, so you should always have something available just in case.
It should also include things like jugs of non-potable water in addition to jugs of potable water. The non-potable water can be used for things like flushing toilets a commonly overlooked but important aspect of losing water access.
It's not that it specifically needs to be non-potable, just that you shouldn't waste drinking/cooking to wash yourself and flush toilets when you don't know how long issues can last.
Rain water and eavestrough runoff water is fine for flushing and cleaning, and it doesn't need to be kept in food-safe containers.
Rookie numbers. The Bundesamt für Bevölkerungsschutz und Katastrophenhilfe recommends to have supplies for two weeks on hand.
In totally unrelated news: Two weeks is also the projected timeframe it would take for a civil war like state to emerge if order can't be established after a country wide emergency.