I have existing gray water line but it is hard to find, where can I find more?
The gray water line is Polybutylene (Poly-B for short) and is no longer manufactured. The product line was discontinued due to the potential for breakdown given certain chlorine levels in the water and a particular kind of fitting, both of which were not an issue in Canada. These pipes, given they are correctly installed, will most likely outlive the house here in Canada and should not be a cause for concern. Poly-B has given way to a number of different waterline manufacturers, the most common one being Crosslinked Polyethylene, better known as Pex, used extensively as a substitute for more expensive plumbing systems such as copper.
See the following link for more info:http://www.pexinfo.com/