Here is a copy of the code relating to gray water systems in New York and Brooklyn. It lays it out pretty clearly. Our green show house has a gray water system and we offer it to anyone wanting to green their brownstone.
Gray water systems are a crucial part of any green renovation. One of the issues we have had is getting it by the DOB. Installing it without them knowing is one thing but really not great. Having them get used to gray water systems and letting it pass without any jumping through hoops is the goal.
We want every brownstone in Brooklyn to have a gray water system. It makes a lot of sense on so many level.
So this code is a great thing to have when the Plumbing inspector comes knocking.