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Partial lead pipe replacement doesn’t completely eliminate water contamination

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New research claims that although pipe line replacements can decrease lead levels in tap water, concentrations spike immediately after line replacement and can remain elevated for months.

Lead in drinking water is a long running problem which can pose a serious public health risk. Utilities are replacing segments of old lead pipes that are responsible for contamination, but the new research, conducted by the American Chemical Society and published in the journal Environmental Science & Technology, suggests this might not be the best solution.

In the wake of the Flint, Michigan drinking water crisis, a host of utilities in the US set about changing parts of old lead service lines to abate the threat of lead leaching into drinking water. The approach has proven controversial, however. Some studies suggest that upgrading segments of service lines instead of a full system replacement might not reduce lead in tap water. Michèle Prévost, Elise Deshommes and colleagues from the American Chemical Society set out to determine just how well such programs might be working.

The researchers analysed water samples taken from household taps in Montreal for up to 20 months. In the homes studied, lead lines had either not been upgraded at all or were in a stage of either partial or full replacement. In comparison to the homes with no line replacement, those with recent partial line replacements had lower lead levels in their water, but 61% of these samples still exceeded the World Health Organisation reference values of 10 micrograms/litre.

Homes that had undergone partial replacement more than two years prior to the study or had received a full upgrade had the lowest lead levels. Significantly, immediately after partial line changes, lead concentrations in one of the houses spiked to more than 25,000 micrograms/litre at the kitchen tap.

The researchers behind the study point out that a number of factors can affect water lead levels in any given home, making their results specific to each house in the study. Nevertheless, the findings suggest that full service line replacement or flushing the replaced pipes before consumption should be priorities. The researchers also note that informing customers of the potential contamination risks and explaining how to address it could help.