The simple fact is, some contaminants require different for removal. In fact, one thing that we strive to get via our tap water is chlorine, which is added at the water treatment facility to "disinfect" the. I loved the simple fact there any video that i could watch on installing the system. https://Sd2c-git.Cores.utah.edu/hershelmccool3/6984690/wiki/A-Think-About-The-Water-Quality-Test