The promulgation of the U.S. Environmental Protection Agency’s (USEPA) Lead and Copper Rule in 1991 created an emphasis on corrosion control in distribution systems and domestic customer’s plumbing.  Currently many Canadian utilities are developing corrosion control strategies for their distribution systems.  General treatment changes that are made for compliance are the elevation of treated water pH and alkalinity by alkali addition and the addition of corrosion inhibitors.

Accepted corrosion inhibitors for U.S. drinking water plants include phosphates, zinc, and to a lesser extent silicate based products.  Some applications require a blend of the various products to address multiple constituents of concern. Since each drinking water system has different water chemistry, each application may be unique.  For example, the key component utilized for lead control is phosphoric acid, or orthophosphate.  Smaller components for deposit control and ancillary issues are polyphosphates.