Water and toilet paper are two popular items. I'm all for people having water on-hand for any disaster. You need one gallon per-person per-day. If you don't need it for the current COVID-19 outbreak, you have it for any future disaster. But, if you are purchasing water by the case like that which is sold in stores, check the expiration on the water bottle.
As for the purchasing of toilet paper, I'm not quite understanding the fascination with this particular product. The coronavirus, to my knowledge, has not been described as causing diarrhea.
I have not ever come across a recommendation for how much toilet paper to have on-hand for disasters. Maybe it should be one roll per day for two people? Or perhaps it should be based on the size/width of your butt? Using 15 inches as an average, one roll for every three days? Whatever the reason, Costco has sold a lot of toilet paper.
Then there is Germany, the term there for hoarding, which is hamsterkauf (hamster buying).
