Lead in drinking water has long been a concern because older pipes can slowly leach lead. That's why it's wise for those living in older homes to let the water run for a couple minutes each morning before taking a drink, so that any accumulated lead can flush out. It's why it's best to cook only with water from the cold tap, because the warm water can encourage more leaching.
Now, a new study suggests old pipes aren't the only source of lead in home drinking water.
PVC piping, now commonplace, may be more susceptible to leaching lead than other types of piping, particularly if those plumbing systems are installed using brass fixtures and pipe fittings, according to the Virginia Tech study, to be published next month in the American Chemical Society's Environmental Science & Technology. Plastic piping is cheaper than the most common alternative, copper.
The leaching comes about because public water systems use a chemical called chloramine to kill harmful bacteria in water, as an alternative to chlorine. A chemical chain reaction, however, makes chloramine produce ammonia, which corrodes brass in the fixtures. That causes the copper, zinc and lead in brass to leach into water.
The study compared various types of piping and found water that runs through polyvinyl chloride pipes produced the worst water quality.
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