Well you'd have to take out the healer part because they're rather rare as far as I'm aware. However a mix of support and some minor attack (you'd be missing out on Ice attacks since you have no official education in water bending. 

Here's the wiki link for all the info
http://avatar.wikia.com/wiki/Waterbending

If I may offer a different suggestion for your character that would explain why he can water bend at a decent level and not have ice powers. 
Have him come from one of the swamp water bending tribes and he came to the city to make a new life for himself be it he failed or not. Just try to give him or her a good spirit because I plan on having our characters meet via a robbery.

Edit: Don't forget while there are a few rivers and lakes through the city they are small so having small water pouches and the like is a must in this situation.