The RO System Steel Tank 11S is assembled using a virgin polypropylene liner, high-grade Chlorobutyl diaphragm, and patent stainless steel water connection. In addition, every diaphragm is post cured to remove any harmful materials or chemicals prior to assembly. This ensures tasteless, odorless, and contaminant-free water, so you know that when you use the tank, you only get pure pristine water when filling your glass.