Steam Breath (Recharge 5–6). Constitution Saving Throw: DC 19, each creature in a 60-foot Cone. Failure: 56 (16d6) Fire damage. Success: Half damage. Failure or Success: Being underwater doesn't grant Resistance to this Fire damage.
More to the point: water is essentially pressure (bludgeoning) plus heat (fire) or cold (cold). In it's neutral state, it doesn't harm. Take six bowls and put one in each: air, fire, water, earth, acid, poison. Stick your hand in each bowl. Fire, acid and poison is going to hurt. Air, Earth and Water only will hurt in certain circumstances (very cold/hot water, very dense packed earth).
The more this has gone on, the less convinced we need specific air, water and earth damage types and just more spells using the elements to do bludgeoning, slashing, cold, fire, or similar damage.