"We'll cross that bridge when we get to it" is not a plan. You've listed that if something happens, you'll make a plan to deal with it at the time it happens. This defeats the purpose of having a contingency plan, where you've asked yourself ahead of time about the "what if's" and developed a plan to address them.
Say for example you do actually lose potable water. In that moment, what's step one? For me, it's determining whether we can continue to operate through the end of that shift (basically whether your process requires water to begin with). Even if your process is dry, loss of potable water means employees can't effectively wash their hands, ergo you'll probably need to shut down production. And the method for shutting down active production should be defined to ensure you don't contribute to any risks with the food.
So next steps: how long are we not going to have potable water? If the crisis spans multiple days, you're considering a full shutdown during that time or bringing in potable water. Sounds good, but where are you going to get it? Last time I prepared a crisis plan, I had reached out to various companies in my area to get quotes for portable handwash stations and tenders of water so we could import and use it for sanitation. If your actual process uses water, which of these companies can get you potable water in quantities needed to continue production? Once that could provide the water we needed were added to my crisis management program (company names and phone numbers),and qualified onto my supplier register.
It doesn't have to be pages and pages of predetermined plans. I'm with you in some sense that assessing an individual situation is something managers and owners need to participate in, and decisions need to be made on the fly. But you should have a basic framework of what a crisis looks like, and some of the basic steps you're prepared to take should one occur. Pro-tip: since you'll revise this plan as part of your corrective action, get your SQF team to sit down and run through what a loss of potable water would mean to your plant, and write it up as your mock crisis for the next year. Since you need to revise it, take full credit for doing the work.