In late January, results were released from our most recent compliance testing for lead required by state and federal regulations. Samples were collected by customers from worst-case scenario homes that were verified to have lead service lines or plumbing. These and other tests indicate that the addition of orthophosphate in April 2019 continues to be effective in reducing lead levels.
We received one hundred sixty eight (168) samples during the sampling period from July 1, 2019 to December 31, 2019. The results were analyzed by a third-party laboratory and calculated to determine whether 10 percent of the total samples exceeded the U.S. Environmental Protection Agency (EPA) lead action level of 15 parts per billion (ppb). The 90th percentile results from the latest round of testing were 10.0 ppb, which is below the action level. According to EPA, there is no safe level of lead. The 90th percentile results from the last round of testing released in June of 2019 were 17.52 ppb, which is above the action level.
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 the worst-case-scenario sites that were sampled exceeded the lead action level. We will conduct another round of compliance testing with samples collected during the sampling period from January 1 to June 30, 2020. Hundreds of water quality tests are taken every month from points throughout the water distribution system to ensure the water is meeting all state and federal regulatory standards. Our dedicated team of water quality experts closely monitor the system every day to ensure safe and reliable service.
In April 2019, PWSA 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 EPA and used in water systems across the world. Our water quality team conducts extensive monitoring throughout the water distribution system to track orthophosphate’s effectiveness and ensure consistent water quality during this treatment upgrade. This stringent monitoring program meets and exceeds state and federal requirements.
“These latest lower lead testing results signals that PWSA is passing another major milestone.” - PWSA Board Chair Paul Leger