Wildfires May Pose Drinking Water Safety Issues

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Two months after a wildfire burned through Paradise, Calif., in 2018, Kevin Phillips, then a manager for town’s irrigation district, walked from one destroyed home to another.

Burned out cars, the occasional chimney and the melted skeletons of washers and dryers were the only recognizable shapes.

“You started to actually be shocked when you saw a standing structure,” he said.

Mr. Phillips, now Paradise’s town manager, was following the team taking samples from intact water meters connected to homes that were now reduced to gray ash. He knew from the Tubbs Fire in 2017 that harmful toxins were likely in the water distribution system: Rapid action would be needed to protect people returning to the community from the dangers of toxins like benzene, which can cause nausea and vomiting in the short-term, or even cancer over time.

Wildfires, which turned skies a dim orange over cities from Seattle to Santa Cruz this year, are increasingly engulfing people’s homes, continuing to rage in California, Oregon, Washington and Colorado in recent weeks. But even when homes don’t burn, other dangers arise in the aftermath, and experts are focusing more attention on what happens to municipal water systems after a fire, when released toxins can get pulled into plumbing systems, and other damage can linger in pipes for years.

After the fire that destroyed Paradise, for example, tests reported in a new study showed benzene levels in drinking water at 2,217 parts per billion. The Tubbs Fire led to levels as high as 40,000 parts per billion. California health authorities say 1 part per billion is dangerous over the long-term, and 26 parts per billion is dangerous for short-term exposure. And many other compounds that end up in water after fire can also create health risks.

“It’s hard enough having the pandemic restrictions,”

How a toxic chromium species could form in drinking water — ScienceDaily

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The water crisis in Flint, Michigan, brought much-needed attention to the problem of potentially toxic metals being released from drinking water distribution pipes when water chemistry changes. Now, researchers reporting in ACS’ Environmental Science & Technology have investigated how hexavalent chromium, known as Cr(VI), can form in drinking water when corroded cast iron pipes interact with residual disinfectant. Their findings could suggest new strategies to control Cr(VI) formation in the water supply.

The metal chromium, known as Cr(0), is found in cast iron alloy, which is the most widely used plumbing material in water distribution systems. As pipes corrode, a buildup of deposits, known as scale, forms on the pipes’ inner walls. Trace chemicals in water can react with scale, forming new compounds that could be released into the water. Some of these compounds contain Cr(VI), which, at high doses, can cause lung cancer, liver damage, reproductive issues and developmental problems. In 2014, California set a drinking water standard of 10 ?g/L Cr(VI), but the guideline was later withdrawn because no economically feasible treatment to remove Cr(VI) from tap water existed. Haizhou Liu and colleagues wanted to find out how exactly Cr(VI) makes its way into drinking water, which might reveal new ways to prevent its formation.

The researchers collected two sections of cast iron pipe from two drinking water distribution systems in the U.S.: one from a system using groundwater with naturally high Cr(VI) levels (11-24 ?g/L), and the other from a system using surface water with undetectable Cr(VI). The team scraped off scale from the pipes and analyzed its composition. The levels of total Cr were about 18 times higher in the first pipe than in the second. In both pipes, chromium existed in two oxidation states, Cr(0) and Cr(III). When the researchers added a chlorine- or bromine-containing