While playing hardcoe,do NOT mess with the game clock...that leads to catastrophic failures.
Your just forced to...return to civilization more.
Several bases of operation have free,clean water.
Food...well theres the survival skill and all that meat you left on the corpses....
This, make regular trips to towns with free preferabley not irradiated water, and just keep checking.
Survival is good, it turns a crappy bit of meat into steak that gives a better bonus. I have mine at 50.
I did however turn down the difficulty because for me stims were pretty much useless when I needed them due to the healing delay, I also havent picked up followers because they die in HC... But so far I enjoy it, it mauy be easier because I have the canteen pre order however.