Dehydration is a mod which adds thirst to the player to make Minecraft more balanced in the view of existing hunger. Drinkable water has polution levels and there are a few ways to clear water just like in medieval times.
Visually the mod adds droplets to the players hud above the hunger bar to indicate how much water is left in the players body. If those droplets are empty the player will start to get damage every 4 seconds.
Thirst doesn’t have the exact same mechanic like hunger. Hunger in Minecraft has saturation which thirst doesn’t. If the players thirst level is below 6 (3 droplets), the player won’t be able to sprint anymore. During sleep the player will loose 2 droplets of water.
Water is classified in three different polution levels:
Dirty: 75% chance of thirst effect, 25s
Impurified: 37,5% chance of thirst effect, 25s
Purified: 0% chance of thirst effect
Water is by default dirty and can be purified in different ways.