Pittsburgh, PA – The most recent round of regulatory compliance testing completed by the Pittsburgh Water and Sewer Authority (PWSA) resulted in a 90th percentile lead level of 5.1 parts per billion (ppb). These samples collected from 158 homes with lead service lines or plumbing are the lowest levels in recent history, demonstrating the effectiveness of adding orthophosphate to PWSA’s water treatment process.
The 90th percentile result of 5.1 ppb is approximately 10 ppb below the U.S. Environmental Protection Agency (EPA) and Pennsylvania Department of Environmental Protection (DEP) lead action level of 15 ppb. This is PWSA’s lowest lead testing result in over 20 years and the second consecutive round of testing below the action level. The results indicate that we are effectively reducing lead levels across our water service area. DEP is expected to certify this round of testing results as early as this week.
Orthophosphate effectiveness improves over time
In April 2019, we began adding orthophosphate to reduce lead levels in drinking water while continuing to replace thousands of lead service lines. 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 EPA and successfully used in water systems across the world. Orthophosphate was selected by PWSA and approved by DEP after an extensive, year-long study of treatment alternatives.
To better understand and implement orthophosphate in the system, we assembled an experienced team of staff, as well as external water quality scientists and state and federal regulators. This group continues to monitor hundreds of additional samples in addition to the compliance testing announced today to ensure that orthophosphate remains effective.
"Water has long been Pittsburgh's most precious resource, and residents should be assured their drinking water is safe and will stay so for generations. It wasn't easy, but we faced this crisis down and will keep doing the work that is necessary to continually improve our water system," Mayor William Peduto said.
“This latest round of testing not only brings us back into compliance with state and federal regulations, but also closes an unfortunate chapter in PWSA’s history,” said PWSA Executive Director Will Pickering. “Ensuring the safety of your water is our number one priority, and we’re aiming to restore our customers’ trust by continuing to optimize water treatment and replacing the remaining lead pipes in our system.”
"Eliminating lead has been a priority for PWSA. I'm amazed at how far we have moved to remove lead from our system,” stated Paul Leger, PWSA’s Board Chair. “Thanks to the PWSA team who made this happen. We have passed all hopes we had for lead reduction and we will continue that work until the lead threat is totally eliminated.”
What is the 90th Percentile?
The 90th percentile is not an average of the presence of lead across our water system, but rather a calculation to determine if 10 percent of homes with lead service lines or plumbing that were sampled exceeded the lead action level. Water utilities like PWSA that have exceeded the 15 ppb threshold, are required to complete two, six-month rounds of testing at or below the action level to bring its water distribution system back into compliance. This round, as well as the testing completed in December 2019, both came under the action level.
Now that we have had two consecutive rounds of testing below state and federal action levels, we are no longer required by law to replace seven percent of the lead service lines in our system each year. We will however continue to conduct aggressive water quality testing and work towards replacing all lead service lines by 2026.
More information about our Community Lead Response and orthophosphate is available at http://lead.pgh2o.com/.