Except it wasn't.
After cleaning out the strainer, the fountain's water now had more lead than before. Tests would show the lead value was actually high in water entering the fountain. So Edwards sent a colleague to UNC armed with a device (an X-ray fluorescence spectrometer) that could assay lead concentrations in plumbing hardware, in place, without destroying the brass.
Paolo Scardina checked the solder at joints in the piping—and that wasn't the source. So he probed further up the line. And that's where he found the now-infamous water-shutoff valves.
UNC replaced both fittings and lead levels plummeted. But still unanswered were why the initial fittings had leached so much lead.
Scardina took the valves back to Virginia Tech where they were cut into pieces and eventually melted down for further analysis. Along the way, Elfland soaked some valving wafers in water to see how long they'd continue to leach lead. When they hadn't stopped by 16 weeks, she gave up counting.
To find out whether these were just two anomalous valves, she had Edwards' team back out to apply their nondestructive testing to another 126 ball valves that UNC had recently installed in new buildings. And 22 percent of these brass parts—including units from three different manufacturers—had greater than 8 percent lead, by weight, on their exterior surfaces. Since Elfland didn't pull them out, she's not sure how high concentrations were on their inner surfaces.
The shed lead ultimately collected in faucet aerators and fountain strainers as tiny particles—shards of metal that would continue to taint any water passing over it. Why the leached lead is precipitating out this way will be the subject of a follow-up paper, Edwards says.
In the mean time, Elfland has calculated how much time it took her team to identify the problem associated with two $20 valves. Assuming standard labor charges for commercial plumbers (had she not been able to employ the salaried individuals on her staff) and all analytical fees, the total came to a whopping $30,000.
And there was nothing special about these valves, she notes. They could have been used in homes.
"If truly leadfree valves were available they might cost more, but I'd buy them," Elfland said. Better yet, she asks, "Why don't we just stop using lead altogether in these devices?"
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