Chemicals that keep drinking water flowing may also cause fouling

The top image shows a thin and stiff biofilm formed from untreated water, and the bottom image shows a thick and soft biofilm that formed as a result of polyphosphate treatment. Credit: Helen Nguyen

Many city drinking water systems add softening agents to keep plumbing free of pipe-clogging mineral buildup. According to new research, these additives may amplify the risk of pathogen release into drinking water by weakening the grip that bacteria—like those responsible for Legionnaires’ disease—have on pipe interiors.

Biofilms, which are similar to the films that grow on the glass of fish tanks, are present in almost all plumbing systems and anchor themselves to mineral scale buildups in pipes. They are teeming with harmless microbial life and incidents of waterborne illness are rare.

"The groundwater that supplies many cities may be high in magnesium and calcium," said Helen Nguyen, a professor of civil engineering and co-author of the study. "When combined with other elements, they can form thick deposits of mineral scale that clog up engineered water systems. Because of this, water treatment plants add chemicals called polyphosphates to dissolve the minerals to keep the scale buildup under control."

A recent study by co-author and civil and […]

Full article: Chemicals that keep drinking water flowing may also cause fouling

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