Pittsburgh Switches to Orthophosphate to Control Water Pipe Corrosion

Crews with the Pittsburgh Water and Sewer Authority (PWSA) (Pittsburgh, Pennsylvania, USA) are currently performing extended water main flushing across the group’s service area to prepare the system for the addition of orthophosphate.

Orthophosphate is a food-grade additive that has demonstrated to be highly effective at reducing corrosion from lead pipes, PWSA explains. Generally speaking, orthophosphate bonds with lead and copper ions to form a protective coating that has a strong tendency to stay in solid form and not dissolve in water.

Due to high lead levels found in some homes, PWSA says it conducted an extensive study to determine if it should use different water treatment methods to limit corrosion from lead service lines and plumbing. The authority currently uses soda ash and lime to control for corrosion.

At the end of a year-long study, however, orthophosphate was found to be more effective than soda ash and lime at reducing corrosion. The Pennsylvania Department of Environmental Protection (Harrisburg, Pennsylvania, USA) agreed with the study’s findings, according to PWSA, and approved the group’s planned corrosion control upgrade to orthophosphate.

Water systems in large cities across the United States have successfully used orthophosphate to reduce the risk of lead in water, according to PWSA officials.

The authority says it is now in the process of constructing new equipment required to add orthophosphate. In addition, PWSA is preparing for this treatment upgrade by flushing the water distribution system. The flushing effort will span several months and take place across the water service area.

Over the next several months, PWSA plans to systematically flush the water system by opening fire hydrants. Flushing clears potential sediment from water mains and prepares the pipes for the protective coating that orthophosphate creates. Flushing could cause temporary brown water for some nearby customers, the authority warns.

Source: PWSA, www.pgh2o.com.