Water sources up in the Sierras, etc. are often cold. For ease of use, I make it a point to scoop water and pour through a mesh coffee filter, add 5 drops of bleach per liter, and wait the 30 minutes (and not bother guessing whether water is warm enough for a shorter treatment period).
Some may view the next step as overkill for clean mountain streams, but I like to drink my water through the Aquamira Frontier Pro filter -- 2 oz. wt. penalty a fair price to pay for clarifying the water, improving its taste (including the elimination of any chlorine taste) -- plus blocking out any stubborn protozoa cyst.
Good to know also that chlorine has a limited shelf life. I use chlorine periodically for my laundry -- so the bottle on my laundry shelf won't ever be more than a few months beyond the purchase date.