nThirst | Water is life.

// Idk how you call this thing but do it
NthirstApi api = new NthirstApi();

// Set player's hydration level to something
api.setHydration(Player player, int i);

// Get player's hydration level, it apparently return an int
api.getHydration(Player player);

// Loads a player, like it pick hydration level in the userdata.yml and it stores it in the server cache or something
api.loadPlayer(Player player);

// REVERSE!
api.savePlayer(Player player);

// Is it enough explicit ?
api.sendGauge(Player player);
api.sendEffects(Player player);

// And there's a new event
@EventHandler
public void onThirstChange(PlayerThirstChangeEvent e) {
  if (e.getPlayer().getLocation().getWorld().getName().equals("lobby")) e.setCancelled(true); // It will prevent players from dehydration if they are in the world "lobby"
}