Keeping your water cool at your basecamp is a very easy thing to do if you are near a stream or river. After you have collected your water from your source, tie some 550 cord to the container.
Tie off the other end of the 550 cord to something secure and let the container float in the water source you retrieved it from. This will keep the temperature of your water to be the same temperature as the water source.
This works great in the mountains where the creeks, streams, rivers and lakes are usually cold year round. Bringing water reservoirs back to your basecamp to early in the day will allow your water to warm up by the evening.