PWSA Prepares Water Distribution System for Orthophosphate

Mora McLaughlinMedia Release, News

Crews begin flushing water system to prepare for imminent water treatment upgrade

Pittsburgh, PA – Today, the Pittsburgh Water and Sewer Authority (PWSA) will begin flushing portions of its water system as it prepares to add orthophosphate to the drinking water. PWSA expects that orthophosphate addition will begin on March 25th and will reduce corrosion in lead water service lines. The decision to use orthophosphate comes after an extensive, year-long study conducted by local and international water quality experts.

Orthophosphate is a food-grade additive that forms a protective layer inside of lead service lines, creating a barrier between the lead pipes and the water flowing through them. It is approved by the Environmental Protection Agency (EPA) and used in water system across the world, including sections of the City of Pittsburgh served by Pennsylvania American Water Company.

PWSA estimates approximately 15% of residential water service lines are made of lead. Service lines run from the water main in the street and carry water into buildings.

System Flushing Before Orthophosphate

To prepare for this water treatment improvement, PWSA will flow water from fire hydrants throughout its distribution system prepare the insides of pipes for the new orthophosphate-treated water. Over the next few months, customers may see crews opening hydrants and performing water quality monitoring.

Customers located near flushing areas may notice temporary brown or discolored water. To clear discolored water, customers can use the following instructions:

  1. Run cold taps at the lowest point in the building for about 10 minutes or until the water runs clear.
  2. If it is still not clear, wait about 30 minutes and try flushing with cold water again.
  3. If the issue persists, contact PWSA Customer Service at 412-255-2423 and a representative can assist in addressing the issue at your property.
Orthophosphate will create a protective barrier in lead pipes to reduce lead levels in drinking water.

PWSA’s Water Quality team will perform ongoing water quality monitoring and analyze hundreds of water samples during the implementation of orthophosphate. The Authority is working closely with the Pennsylvania Department of Environmental Protection (DEP) to ensure the transition to orthophosphate goes smoothly.

“We’re excited about applying this upgraded water treatment method to protect our customers and reduce lead in water,” said Executive Director Robert A. Weimar.

“Orthophosphate addition is the interim step to reduce to the risk of lead in water found in some homes. Our long-term goal is to remove all lead service lines from the system. This year alone, we plan to replace over 4,000 service lines,” he continued.

The 2019 lead line replacement program will start in the coming weeks. Customers can learn more about lead in water and PWSA’s Community Lead Response programs at

Flushing Schedule: March 18 – March 29
West, South, and East End Neighborhoods


  • Esplen
  • Sheraden (small portion)
  • Westwood (small portion)
  • Ridgemont (small portion)
  • Elliott
  • West End


  • Duquesne Heights
  • Mount Washington
  • Allentown
  • Southside Slopes


  • Squirrel Hill South
  • Greenfield
  • Hazelwood
  • Glen Hazel