The Pittsburgh Water and Sewer Authority (PWSA) continually monitors and tests the drinking water in its system to ensure that it provides quality water to its customers. As part of these quality assurance and compliance efforts, PWSA tests drinking water for pH, which measures acidity or basicity on a scale of 0 - 14.
According to its permit from the Pennsylvania Department of Environmental Protection (DEP), PWSA must maintain pH levels in the water system between 7.2 and 8.6. Testing at three sites in June of 2016 produced samples that indicated a pH level of 8.7. Those sites were retested the following week and found pH levels back within acceptable range.
The pH levels found in June 2016 do not indicate a risk to health or the water supply. In March 2016, the U.S. Environmental Protection Agency (EPA) released a paper suggesting that an upper limit for pH in water distribution systems may be unnecessary, and that higher levels of pH can help reduce corrosion in lead and copper pipes.
PWSA Interim Executive Director Bernard Lindstrom said, “PWSA is improving its testing processes to account for random variations of pH in its large drinking water distribution system to avoid incidents like this in the future. The Authority is also studying alternative drinking water treatment chemicals to ensure our customers benefit from the best treatment methods available.”
PWSA’s DEP permit issued in 1997 requires that when a pH level is exceeded, resampling must take place immediately, and have no more than nine calendar days total within a six month period out of range. The DEP is requiring all PWSA customers to be notified because resampling took place a total of 13 days after the initial exceedance. All PWSA customers will receive a mailing this week that includes a formal notice, and a “Frequently Asked Questions” document explaining the incident.