I am a big fan of Platypus hydration bladders and I normally carry a 3L reservoir with me when I’m backpacking.
Platypus bladders are different from Camelback reservoir, which I have used in the past, because they have a much smaller opening screw top openings. This is important when you are cooking and you need to pour some water into a pot.
Platypus bladders also stand up by themselves on a flat surface which is useful when filtering, transferring water between bladders, and again while you are cooking.
In the evening when setting up camp, I’ll go to the water source and fill my two 1 liter water bottles and my 3L Platypus bladder. They actually hold about 3.5L. I use the water in my bottles to cook dinner and keep the platypus full until the next morning for breakfast and to fill my first set of water bottles for the day. That way, I don’t have to filter and/or purify water in the morning and can break camp quickly when the sun comes up.
I’ve read about people who have had problems with their Platypus bladders because the caps can leak. I solve this problem by wrapping the threads of the opening with teflon tape, also called plumbers tape, which gives the caps a very snug fit. I learned that trick in organic chemistry lab in high school.
The Platypus bite valve does leak because it does not come with a locking mechanism that turns off the flow from the bladder to the bite valve. I use a Camelback bite valve instead, which does have a lock. I attach it to a Platy tube and never have any leaks that are not due to forgetfulness.
I also use a 1L platy for carrying stove fuel for my alcohol stove. This bladder is well-marked with skulls and cross bones to prevent people from drinking from it.
Platys are pretty indestructible and easy to clean using water purification tablets. I have however had some issues with them freezing in colder weather and the 3L size is awkward to slip into your sleeping bag. When the temperature dips below freezing, you are probably better off switching to a wide mouth Nalgene bottle. If you carry them upside down during the day, the tops don’t freeze shut.
A 3L platy weighs 1.4 oz. and a 1L bladder weighs 1 oz.
Disclosure: The author owns this product and purchased it using their own funds.
Written 2008. Revised 2013.