DDO has a lot of cold baased spells but sadly not that much "water" based. The unique water spell is the Horrid Wilting. That said, would be cool to see more water based spells. Some suggestions :

GEYSER

Spell level : 6

This spell creates on the ground, a stream of hot and deadly air dealing d4 caster * level fire damage + d4 * caster level bludgeoning damage each 2 seconds and pushing smaller enemies away from the center. Forcing then to do a mobility check or be kncoked prone. The spell lasts 10 second + 2 second each 4 caster level.

Compressed water ball

Similar to fireball but deals bludgeoning damage and has a smaller radius of explosion.

TIDAL WAVE

Similar to Pathfinder Kingmaker tier 9 magic.

Water Jet

Fires an jet which deals slashing damage

MARID FORM

Assumes the form of a Marid. IMHO, Sorcerer Elemental savant capstone should be more about assuming Efreets, Djins, Daos and Marids instead of just an elemental. We are talking about lv 20 casters here. If a lv 3 pale master can become a lich, a lv 20 sorc should be able to become a "geniekind"