Insatiable Thirst

This spell instills in the victim an uncontrollable desire to drink. The victim is allowed a saving throw to avoid the effect. If the roll is failed, the creature must consume any potable liquids it can find (including magical potions, which might result in strange effects if potions are mixed). Although poisons are not considered potable, a victim may not realize that a liquid is poisonous.
The victim will not consume a liquid he knows to be poisonous.
No matter how much the creature drinks, its magical thirst is not quenched until the spell ends. During this time, the creature can do nothing but drink or look for liquids to drink. Victims of this spell believe they are dying of thirst and (depending upon their nature) may be willing to kill for drinkable fluids.

[Tome of Magic]

School: Enchantment/Charm
Level: 2
Rarity: Uncommon

Range: 5 yards/ level
Components: V, S
Duration: 1 round/level
Casting Time: 2
Area of Effect: One creature
Saving Throw: Negates