Like many others here I carry several platypus containers, generally two of the 2L and one of the 1L, along with the drinking tube and bite valve.

It isn't just a matter of whether one water container springs a leak -- although I did have one platypus develop a pinhole-sized leak, once. There are other things that can happen.

Like being fumble fingered and dropping a cap into a river, or even a whole water bottle. Or stepping on the cap where you set it down for "just a second" on some river rocks. Or leaning your pack against a tree and accidentally squashing the bite valve open, out of sight, so half your water siphons off as you sit and take in the scenery.

Having 5L of capacity also gives me more flexibility in making a dry camp.

But this is just my way of doing it. You don't have to do it the same as me.