The (Clack WS1TC Control Valve) used in the PhSmarte 1000 Whole House System has earned NSF Standard 61 Certification:
NSF/ANSI Standard 61 (NSF-61) is a set of national standards that relates to water treatment and establishes stringent requirements for the control of equipment that comes in contact with either potable water or products that support the production of potable water. The tests vary from a basic cold water test using water at different pH levels, to the more challenging chemical certification. In all cases the equipment is tested before and after exposure to a given fluid to determine whether anything has been leached out or extracted from the equipment. NSF-61 was developed by the National Sanitation Foundation (NSF), a global independent public health and environmental organization, and the American National Standards Institute (ANSI), which oversees the consensus for developing standards for manufacturing and procedures in the United States.