Have to say I'm with Bob on this one. I've never had a bladder, I'm either carrying my flask of coffee (probably appreciated by my fellow walkers
) or a Sigg bottle, the latter very good at keeping drinks chilled. But they don't last forever, I'm on my second one now, in 40 years
I keep sterilising tablets for when the water source is low down or suspect, but hardly ever use them.
Personal preference, but I also like to stop for a drink, take off the sack, soak in the views etc.