At the very least, you'll want some type of plastic bottle. You can cut the end off of your plastic bottle and layer in ground ( smashed ) charcoal from your camp fire along with cotton, sand, grass, most anything you can get your hands on to filter out the different sized particles. Charcoal being the most likely to weed out micro organisms.
Or, with most water bottles you can string it above the fire and bring the water to a boil before the plastic melts if you're careful. This typically works best when the water bottle is completely full and capped.
If all that fails, remember that it's easier to treat diarrhea tomorrow than heat stroke today .