I thoroughly agree that consideration about a long term water supply is essential. Too many assume that town water will continue to be available, even in a crisis. There are just too many past examples to show that this idea shouldn’t relied upon.
Many water supplies depend upon electric pumps to keep the flow going, which make them vulnerable. Questions that can be considered would be: Are there standby generators to keep the flow happening? Is there fuel for the generators, and if so, how much? Do the managing authorities assume that any emergency will be over in a few days? Have they even thought about this at all?
Many authorities don’t think much about emergencies and contingencies, and in so far as they do they tend to assume any disasters will be local and temporary, and so under-fund emergency services and infrastructure. This, in fact, is why we prep; because we can’t rely on the government to save our chestnuts out of the fire when a crisis comes along.
I like to give myself as many options as possible when I think about prepping, so some things worth considering are (as has already been said) finding a location that is near a reliable water supply, stocking up on purchased water, having rain catchment storage, underground bore water, devices for extracting water from the air. There is plenty of info about these found on the web or youtube. Think about short term and long term possibilities. Filling the bath tub might be okay for a few days, but having some long term options is good if one can do it.
Of course not everyone can take advantage of all possibilities; for instance, a poor person can’t afford to buy some land near a water supply. But the important thing (though I’m sure people here already know this) is to not assume that water will always be available and to prepare in whatever ways we can.
Bugs Bunny: "I speak softly, but I carry a big stick."
Yosemite Sam: "Oh yeah? Well I speak LOUD! and I carry a BIGGER stick! and I use it, too!" BAM!