Effectively, you have 2 "staminas" in game right now. Your current stamina bar, and your reserve stamina in terms of water you're carrying. PvPers continually have the issue of "we need to carry more water at the cost of equipment slots, but rather than being a strategic choice in most cases water just completely eclipses any alternative"
Rework stamina bar into "winded debuff", recovers exactly like normal. Instead of drink, we have "second wind" which refills the stamina bar. This drains our reserve stamina and energy and is in all ways directly equivalent to drinking water.
What we call the "Stamina bar" in this new system is the equivalent of water stored in your inventory/belts in the current system. It's recovered by "resting". Resting is basically the equivalent of refilling your water jugs. Could be done at any water tile, well, barrel of stamina regenerating liquid, cistern of stamina regenrating liquid, and takes a non-zero amount of time that's not too arduous. Maybe max 30 seconds, scaling off how much you're missing. Could be accompanied by a little animation of your hearthling sitting on the ground and drinking from a cup.
Another question is: Should energy burn happen while using second wind, or should it happen during resting?
In short: I'm suggesting we replace water with a system that is functionally identical, but everyone has the same amount of water on them for no equipment or inventory costs. How much energy is drained and how much total water equivalent is "carried" should 100% be determined by the PvPers who are most negatively impacted by it. Literally everyone other than pvpers will benefit from this system (pvpers usually carry absurd amounts of water, so it should be a buff for everyone else), pvpers will get more gear choice.