At the WLC, we teach students to make transpiration bags over solar stills. Water is more easily collected this way and it requires almost no energy to set up. While stills have their place, they aren't the best option in every climate.
Here is a brown flag related to water,
"You can't get sick from drinking stream water in the winter"
Sure, fewer animals and insects will be active but there are plenty of nasties that can hurt you from drinking untreated water.
Here's another one:
You can drink water from fast flowing water and not get sick. B.S. Granted in some situations it can work, but would trust it? Heck no!
Always treat your water no matter what. Just to avoid the nasty bugs.