Thirst

is a Tier 1 Sense Path Spell.

The caster makes a subject feel thirsty (even if they've just drank). At Tier 2+, the subject can't help but drink if something drinkable is available; at Tier 3+, the subject becomes desperate for water and it impacts their actions. At Tier 4+, the thirst becomes debilitating. Doesn't increase the subject's need to drink.