Is the New Water Test to Detect Lead Accurate?

The four-bottle test to detect lead is now replaced with a one-bottle test

Michael Coblenz, concerned about the effects of lead on his 3-year-old child, requested a test kit in January, and the Pittsburgh Water and Sewer Authority sent him one with four bottles.

He let his water sit for six to 10 hours and filled bottle one right after turning on the tap. The instructions told him to fill bottle two immediately after filling bottle one.

Before filling bottle three, he had to run the water until he noticed a change in its temperature and then let the water run for at least two minutes more.

This is where Coblenz, 33, a Carnegie Mellon University student pursuing a Ph.D. in computer science, ran into trouble.

“I waited two minutes, and I didn't know if it was cold enough,” he said.

“I could see how an easier test could be useful,” Coblenz said.

PWSA agrees. The water authority abandoned the four-bottle test that tripped up Coblenz and switched, first to a two-bottle test and then to a one-bottle test by March. The one-bottle test used by PWSA now asks customers to not use their water for six to 10 hours and then take a sample from the tap immediately after turning it on.

That's it — one bottle, one sample.

Water-quality researchers worry that cutting the number of samples in each test will cut the amount of information gathered. Marc Edwards, a Virginia Tech researcher that probed Flint's water, said that while the federal Lead and Copper Rule, which limits the amount of lead and copper allowed in the water, requires testing with only one bottle, proposed revisions to the rule call for two bottles.

“Many other cities are adding a second bottle now, because that is how you identify a water lead problem coming from the lead service line,” Edwards wrote in an email to the Tribune-Review. “The net effect of sampling one bottle instead of two or four is to dramatically reduce the likelihood of identifying lead. ...”

PWSA on July 1 released recent water samples from nearly 400 homes that showed more than half with no detectable levels of lead and 5 percent at or above the federal limit.

Lead isn't in the water when it leaves PWSA's treatment plant, and the authority has no lead pipes in its system. Lead leaches into the water when it passes through lead service mains or over lead solder inside homes.

Partha Basu, a researcher at Duquesne University, said two or four samples taken at different times can show where the lead may be coming from. A first draw tests the water sitting in the faucet. Letting the water run can test water in the internal plumbing, the lead service line and main service pipes.

“If you only do a one-bottle test, and it turns out high, you don't know where the problem is,” Coblenz said. “If we had done a one-bottle test, it would have been 13 and that would be the end of story.”

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