“Why bottled water?”
So that when you and everyone else in your household are laid up with the flu you can hydrate without getting out of bed.
Staying hydrated is critical when you have a fever. It may keep you from cooking your brain.
But . . . but . . . but . . . if I am that sick someone will take care of me — except if everyone in your house is that sick, too. But . . . but . . . but . . . if that happens I can get a doctor or go to the hospital — except if this is a 1918-type influenza the doctors will be just as sick and the hospitals will so crowded they be laying out patients on the floor.
Read some accounts of the 1918 pandemic. It got THAT bad. If we have a true pandemic a la 1918, you will be better off staying at home and staying in bed than doing anything else. Remember, medical services cannot really do anything for you other than let you heal yourself with a virus. Antibiotics may help with secondary bacterial infections, but they do nothing against viruses. Tammiflu apparently helps, but I’d bet that runs out almost immediately.
Bed rest and hydration are about all that can be done until you heal yourself. And stay in bed several days after you start feeling better. Lots of flu victims died exerting themselves after feeling better back in 1918.
This probably increases the death rate in countries where the practice is if you don't show up for work, then you don't get paid. People go back to work as soon as they feel able to walk.