If I recall correctly, I read that the foodco could purify water directly into the vehicle tanks? I haven’t been able to do that, or find where I thought I read it. Am I imagining things, or did I just place things incorrectly in my vehicle?
And a tip: Labs are not nearly as bad as people say they are if you move slowly and think ahead. You can go in with just a pocket knife, a few rocks, and a bit of food and be fine, as long as you use shift+X to peek around corners to check for turrets. If you see one, hit esc and close the door. Keep to the walls and you will avoid practically all threats. When you can reliably take down a manhack (a tossed rock can often kill in one hit with just a little skill) you can even intentionally fail hacking computers to get combat knives and plutonium from them. Remember that if there is ever a threat, step directly away from any nearby computer, as that will make it impossible for the security bots to shoot you if they show up. Keep to the darkness, avoid light. And if you kill manhacks by tossing rocks, you can even kill the security bots by tossing rocks/manhacks/knives at them.
Personally, I find labs to be some of the safest areas in the game, though I do play with 5x or more zombie spawns. That said, ice labs suck.
Another good thing to do: if you find military ids, find a bunker or two and only open the top to start with. The inside is safe, so you can flip on your flashlight to look around. Only open a room that has explosives in it that you can use immediately. Packed LAWs are awesome, as you can immediately bust open any other room with one by standing on one side of the hall and shooting the glass on the other side. I reccommend aiming for another room with explosives, if possible. Never enough boom. C4 can also be dropped right beside the glass to bust it open, and I think grenades work, but I haven’t tried those yet.
I have begun to change how I start to instead go on a mad dash to find a working motorcycle, then race around the countryside looking for science and/or military id cards and somewhere to use them. Both areas are extremely safe compared to the towns.