Cactus Flesh

Call it a canteen that grows out of the sand. The game describes it as flesh of a cactus that contains water, and says nothing about hunger, so treat it as a drink you chew rather than a meal.

The desert is where it earns the slot. You are crossing the dunes toward a monument, the small water bottle ran dry an hour ago and the nearest river is far behind you. The cacti around you are the only water in sight. Hit one, pick up the flesh, eat it on the move. Mind the spines: standing in a cactus hurts.

Away from the sand it barely matters. A filled bota bag on your belt or a water jug at base does the same job for longer, and ten pieces per slot is not much of a supply. Eat it where you find it and keep your bag for loot.