As part of the Pittsburgh Water and Sewer Authority’s Community Lead Response, we began to use orthophosphate to reduce lead levels in tap water in spring of 2019.

A year-long study found orthophosphate to be more effective at reducing corrosion than our previous treatment method using soda ash and lime. The Pennsylvania Department of Environmental Protection (PA DEP) agreed with the study’s findings and approved corrosion control upgrade to orthophosphate. Water systems in large cities across the country use orthophosphate successfully to reduce the risk of lead in water, including sections of the City of Pittsburgh served by Pennsylvania American Water Company.

We have built four new facilities to add orthophosphate to the water distribution system. Beginning in spring 2019, we are flushing the distribution system by opening hydrants in preparation to add the orthophosphate.

Frequently Asked Questions

Orthophosphate is a food-grade additive that we will begin adding out our treatment plants to help reduce lead levels in water. When water with orthophosphate runs through the system, it will create a coating on the inside of lead service lines, creating a barrier between the lead pipes and the water. This is called “corrosion control”. PWSA currently uses soda ash and lime for corrosion control but has found that orthophosphate will work even better.

The Environmental Protection Agency (EPA) and the Pennsylvania Department of Environmental Protection (PA DEP) recognizes orthophosphate as an effective additive in water in reducing lead levels. It is also recognized as safe by the U.S. Food and Drug Administration.

PWSA conducted a year-long study of several different additives that are used to reduce lead levels in water. After finding that orthophosphate would be most effective for PWSA’s system, the research was reviewed extensively by the PA DEP before being approved as part of the treatment process. Orthophosphate is used for corrosion control in Boston, Washington, DC, Cleveland, and Philadelphia. It is also used by Pennsylvania American Water Company who serve some customers in the City of Pittsburgh.

PWSA exceeded the action level for drinking water in June 2016. Since then, we have been working to aggressively replace lead service lines. However, replacing every lead service line will take years. In the immediate term, an effective solution to address high lead levels is to use the most effective corrosion control, which benefits our entire drinking water system.

After approximately one year of orthophosphate being used in our water system, we saw the lowest lead levels in over 20 years. This treatment method will greatly reduce the risk of lead for our customers while we work to remove the source of lead from the water system.

PWSA’s Water Quality team will perform ongoing water quality monitoring and analyze hundreds of water samples during the implementation of orthophosphate. They will also provide comprehensive water samples to state regulators on an annual basis. The Authority is working closely with the Pennsylvania Department of Environmental Protection (DEP) to ensure orthophosphate continues to work effectively.