SenSafe® Free Chlorine Water Check test strips are the ONLY EPA APPROVED test strips used for drinking water compliance monitoring. They combine a wide range of water quality detection with our patented Free Chlorine indicator. Designed to resist interference from monochloramines, Free Chlorine Water Check is the ideal product when testing drinking water quality. Free Chlorine Water Check is perfect for determining whether or not you have the correct amount of sanitizer present. No external chemicals are needed to perform the water quality test. The unique, patented, SenSafe® strip allows for low level detection without sacrificing accuracy.