Thats when you make each environment have its own water type :P. General "this is water" no matter where you are, can make do but the best systems uses different attributes for each area (more then just color).
Seeing as swiming will not be out on realese of ARR I'm not so worried about it. But I really hope they dont plan on using the same water system once they are pumping out that water expansion.
Or that they programed themselves into another corner and cant change anything without a total redesign.
