They're talking about "for general disaster preparedness" in this comment. The OP specifically mentions not worrying about water in the case of COVID specifically.
My guess is GP is suggesting water for disasters, such as earthquakes, floods, or other situations where water supplies will often be compromised. I say that because GP differentiated between pandemics, and natural disasters, and specifically mentioned his/her experience working disasters in the national guard. I believe the distinction being drawn here is that, as far as we know, infrastructure hasn't been compromised by COVID-19
