Does it hold water?  Does it not leak?  Does it hold enough water? If so, it is fine.  you can tell I am an old desert rat.....

one thing I like about bladders is that they position the weight of the water right where it should be.  I have all sorts of canteens, including several Nalgenes, and even more repurposed sport drink bottles.  If I had only retained a classic GI metal canteen, I could start a canteen museum.  I generally include a metal cup which fits snugly around the base of the drink bottle or the Nalgene.

And I always try to carry enough water.....

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