Another item you will need is some test strips for checking pH of water. They are cheap and you can get at any pharmacy. Since you will be making this want it to be within a pH range. While there check for the availability of trisodium phosphate, a cleansing agent. Won't need much, down the line will need about 1.25 teaspoons per gallon of water.

While I don't recommend any specific lab for testing, Psychemedics uses the lowest cutoff and has a home test available. HairConfirm is another that seems more widely available (pharmacies, stores, etc). I have no specific direct experience with the latter. They are about same price.