Thirst is one of the many new survival mechanics of Medieval Unlimited.

You can view your thirst bar in your HUD above your hunger bar. As you play, thirst will slowly drain, and if you run out you will start to die of dehydration. To fill your thirst you will need a Canteen. Canteens can be filled by right clicking any water source, and have 15 drinks per fill.

View how to craft a canteen in /ia, Drinks and Canteens.