Thirst and Quenched
The two numbers
Thirst runs from 0 to 20 and is drawn as ten droplets, so one droplet is two points. New players start full.
Quenched is a reserve that sits on top of it, exactly like saturation sits on top of hunger. It is drawn as a lighter outline over the droplets and starts at 5. Anything that would cost you thirst eats the reserve first, which is why a good drink lasts longer than a bad one even when both fill the bar.
When the reserve runs out the droplets shake, the same warning the hunger bar gives.
What drains it
Thirst uses the same exhaustion vanilla already tracks for hunger. Sprinting, jumping, swimming, mining, attacking and taking damage all count. Every 4 points of exhaustion spends one point of quenched, or one point of thirst once the reserve is empty.
With AppleSkin installed, the thirst bar also gets a dithered exhaustion strip behind its droplets. It fills from right to left as exhaustion approaches 4 and follows AppleSkin's Food Exhaustion HUD Underlay setting. AppleSkin is optional; without it, thirst and quenched still work and render normally.
Sitting on a horse, a boat or a minecart costs nothing. Creative and spectator players are ignored entirely.
On top of that, the world you are in scales the cost:
| Where you are | Effect |
|---|---|
| A hot or dry biome | Drains faster |
| A cold or rainy biome | Drains slower |
| The Nether, or any dimension where water evaporates | A flat, much heavier rate |
Two potion effects push back. Fire Resistance halves the drain, and Fire Protection on your armour slows it further, down to a quarter of normal at the deepest. Nausea does the opposite and adds a steady extra drain while it lasts. Hunger does not, because the exhaustion it already causes is counted once rather than twice.
On Peaceful the bar refills on its own instead of draining, unless the server turns that off.
Every one of these rates is a setting. See Configuration.
Running low
At 6 points or below you cannot start sprinting, the same cut-off vanilla uses for hunger.
Natural healing stops until thirst is nearly full. At 19 it starts again, though the quick saturation healing only fires an eighth as often. Health you did not regain does not cost you any food, so a dehydrated player does not quietly starve as well.
Hitting zero
An empty bar costs half a heart every two seconds. The damage ignores armour, and the death message reads died from dehydration.
Difficulty decides how far it goes. On Easy it stops once you are down to five hearts. On Normal and Hard it will kill you.