Clean water is healthy water. Water filtration systems help clear out contaminants and keep hard water from becoming an issue. City filtration systems take care of the majority of water contaminants, but not all of them — this includes chlorine, fluoride and some other contaminants like PCBs, THMs and heavy metals.
Installing a water filtration system for the entire house not only keeps these contaminants at bay, it reduces the pressure on small system filtration systems like the ones on most refrigerators.