So this monastic tradition focus more on the idea that water can be both soft and soothing, with the fact that its really really really deadly.

The 3rd level ability is designed in around the same time as the fire one so i thought about what could visualize the flow of water through martial art. As per the other monks, 3rd level need to be the main/shining part of the monk. Also added ray of frost and shape water cantrips for coolzies

6th level ability is the so cald soothing idea of water. The reason its limited to a long rest is that bonus action heals are big and I don't want it to be better than the open hand heal. Resistance to cold seems fine both thematically and mechanically.

11th level ability plays again with the high power level you could have. Freeze snap is the I freeze the move. Balanced by 1 ki and action therefore stopping you from using monks amazing multiattackbillionpowerstrike. Control Water seems like a thing that it should have and the current action + 1 ki seems fine for the price.

17th level ability is always fun on monks. This one I tried playing with the ice prison that Aang was in at the start of avatar. Decided that the imprisonment spell was close enough so gave it a bit of flavor and allows it to be Disintegrated.

Anyway, without further ado...