If there is NO cross connections there is absolutely not reason for testing, at least in a home situation. Understand should be checked for any cross connections with new construction and maybe every few years due to some homeowners playing games. Other hand with water testing this can be confirmed in the water lines up and down the system without going into homes, that is my take on it, I know what a cross connection is and what it could cause, but also used to have a water license myself and know what can be done and not done outside the home. Also not sure all the chloride tests that are supposed to be done per the EPA, I know that a certain percentage of serviced homes or area are to be tested, so far I've never been asked to have it checked in my homes anywhere, I tested many locations when I was the water treatment operator of record for SIUE