I don't know that I'd want to take my chances drinking that water, but...

I keep an instant ice pack in my FAK, as I've found that getting cold on something right away can make the difference between an ankle you're walking on the next day and one that you're limping on for a week. Numerous first aid applications there.

These days I always keep one in my hydration pack for long trail runs in case I find myself having problems coping with the heat (or in case I do something stupid which would require immediate icing).

In the winter I carry a couple of reusable heat packs. Although I wouldn't count on them to keep me alive they do provide a little creature comfort when things get too chilly.

When you step out that door in the morning you never really know what you're going to encounter.