I did a check for chlorine a number of years back to see if the carbon block on my RO system was still doing it's job. Seems to have worked pretty well for me, the evidence is clear in the photo below. Left strip was sample of water after carbon block, right strip was tap water. Unless you're colour blind it's fairly obvious that the chlorine tab for the tap water is indicating the presence of chlorine. In the end, on any given day, depending on how your water supplier treats the system & other variables, results may vary.
