How can you even end up in that situation? I been playing since alpha 9 or 10, and I've not once even gotten close to starving or dehydrating not even when I was new, backl in earlier alpha's u could not boil water at all without a cooking pot, and the forge recipe was loot only. Usually It never drops below 50% and that only happens if I am really involved in something like a build and forget to watch it. Water I keep above 75%, as once it hits 74% you take a 20% stam regen hit (4/tick instead of 5/tick), Its noticable.
Its even weirder how people can have food/water issues with the quest system, since when you start the quest it turns it back to a fresh poi full of loot. I often don't even have food/water issues even on day 1, there are many sources. Traders, Vending machines, Animals, random crops, Dysentery is no longer fatal in the last few alpha's it just takes a while to wear off, if your worried wait till u find a vitamin, pop those then stuff yourself with whatever as it makes u immune to dysentery/infection etc. Which means you could eat those old sham sandwhiches if in a bind. By day 7/14 in Vanilla I usually have stacks of meat just sitting in storage unused, as other food is abundant.
A few buried supply quests on day 1 can also set you up nice food/drink wise, as well as make you some dukes to buy more.