University study suggests softening agents for biofilm may lead to fouling in drinking water


By Veronica Mierek , Contributing Writer

City drinking water systems may be in danger of fouling due to the effect of softening agents on biofilm, according to a research from the University.

Biofilms are present in nearly all plumbing systems, according to the press release. Most biofilm is harmless, but it can form mineral scale that can clog up or block water pipes when combined with other elements.

Many water systems add softening agents to the water supply in order to prevent mineral buildup. According to the press release, these softening agents cause biofilm to grow thicker and softer and make it easier for the biofilm to detach.

“The reason that we worry about heavy biofilm is because pathogens can hide in the biofilm. If the biofilm is easy to be broken off from the pipe, then the broken pieces may have the pathogen,” said Helen Nguyen, civil engineering professor at the University.

The thicker the biofilm, the more bacteria it contains. In buildings where the water has remained stagnant for a period of time, the bacteria can pose a public health issue, Nguyen said in the press release. However, some sort of anti-scalant chemical is still required to maintain adequate water flow.

Current regulations are inadequate for private property, Nguyen said. The water main and city water pipes are regulated by the city or water company, but once the water reaches plumbing on private property, it ceases to be regulated.

“(The water system is) out of sight, out of mind, no one saw it and we really don’t maintain it until it breaks,” said Nguyen. “So the first thing I would say is, you know, we have to pay attention to our infrastructure.”

Nguyen said she suggests releasing the water in stagnant pipes. She said it is easier than some of the other possible methods of solving this problem. According to the press release, a better understanding of water chemistry is where the most realistic solution will come from.

“We want to understand what chemicals we can use in the drinking water to prevent scaling, to prevent corrosion, but doesn’t help grow biofilm,” said Nguyen. “That’s what my lab is all doing right now, and we have been working on this job for years, actually, because it takes a very long time to do this work.”

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