Are lead levels in Pittsburgh drinking water really going down?
The last three rounds of lead testing showed good news for the troubled Pittsburgh Water and Sewer Authority. Lead levels were trending slightly lower.
This winter, PWSA is poised to comply with the Environmental Protection Agency's lead contamination threshold — lifting a cloud that has been over the authority since summer 2016.
Although the lead samples have decreased — from a 90th percentile result of 22 parts per billion of lead to 15 ppb — the decrease has not been significant enough to show levels are decreasing substantially, PWSA interim Executive Director Robert Weimar said.
“Does the difference between 15 and 22 really mean anything? I don't think so,” Weimar said. “I don't think a few parts per billion are big differences.”
Even if the authority clears the threshold this winter, Weimar said he and his staff won't be satisfied until the level is zero — a goal that's unlikely unless the authority changes the chemical makeup of the water.
Since summer 2016, the authority has not altered the chemical makeup of the water — until now.
In July, the authority added liquid lime back to the water — an element of the authority's corrosion control that was removed in August 2016 when its dry lime feed system broke, PWSA spokesman Will Pickering said.
Lead compliance samples have not been submitted since. The next round will be collected this winter, which could show a sharper decrease because of the chemical.
“The last round of samples doesn't reflect it, but the next should,” Weimar said.
PWSA will seek DEP approval to make a more drastic change to the water to decrease lead levels by adding orthophosphate or another chemical that would reduce the amount of lead particles that can leach into drinking water from lead pipes.
The authority plans to have that change in place by March, Weimar said.
Marc Edwards, a Virginia Tech water quality expert who helped expose the water crisis in Flint, Mich., said if PWSA adds orthophosphate, a single-digit lead level would be possible.
“Very good things tend to happen when orthophosphate is added to systems with lead pipe,” Edwards said. “Single digits are probable within 18 months, as long as they do not skimp on dose. In England to really control release from lead pipe, they dose about one part per million as phosphorus, which is about three to four times the typical dose in the U.S.”
PWSA is also coating lead pipes with epoxy to see if it decreases lead, on a trial basis.
Even though PWSA's lead level has been decreasing, residents living in homes with lead lines should not be drinking the water straight from the tap without filtering it for lead, especially if pregnant women or children under the age of 5 are in the home, Edwards said.
EPA recommendation not followed
PWSA has not been following an EPA recommendation that water systems with high lead levels take lead samples from the same homes in each round to measure progress.
Only 49 homes submitted samples in all three sampling periods, a Tribune-Review analysis found. That's fewer than half of the 100 to 150 homes that submitted samples in any given sampling period.
The samples are then sent to the DEP to calculate whether at least 90 percent of results were under 15 ppb, meaning PWSA clears the EPA threshold.
If the 90th percentile result is calculated using only the 49 homes that were sampled all three times, the lead level in the water would be about the same now as it was in summer 2016: hovering around 18 ppb.
Paul Schwartz, with the D.C.-based Campaign for Lead Free Water, said it should not be difficult for a system with at least 17,750 lead lines to find 100 homes to sample each time.
“You have thousands of lead pipes in Pittsburgh, there's no reason you can't come up with the samples from the same 100 homes that have lead pipes,” said Schwartz. “Based on their testing, there's no way for them to know that lead levels are coming down.”
Samples from all the same homes aren't submitted each time because PWSA relies on customers to voluntarily take samples and mail them in, so it sends sample kits to more homes than it needs, said Weimar.
“We can't demand that these people provide us samples,” Weimar said.
In summer 2016, the authority sent the sample kits to 125 homes that have lead lines or are likely to have lead lines.
It narrowly got the minimum 100 samples that it's required to turn in, so for the next sampling periods, it expanded the number of homes that received sample kits to 200, Weimar said.
In the second round, it received 149; in the third, 128.
For the next round of testing, the authority plans to send the kits only to homes with confirmed lead lines, which will also increase accuracy, Weimar said.
“We are concerned there may have been replacements we may not be aware of,” Weimar said.
Theresa Clift is a Tribune-Review staff writer. Reach her at 412-380-5669, email@example.com or via Twitter @tclift.