Notice PFAS and contaminants sitting around in the filter. from: https://www.nytimes.com/2023/05/30/well/live/water-filter-bacteria-pfas.html
. . . Most filters contain activated carbon to capture contaminants, which can be used in pitchers, refrigerator dispensers, faucet attachments or systems installed under the sink. Activated carbon is good at removing many chemicals and metals but not all (it doesn’t capture nitrate, for example), and it cannot filter out most bacteria. The American National Standards Institute and NSF — two independent groups that evaluate product performance — have established standards for water filters. Companies aren’t required to make products that meet NSF/ANSI standards, but because “there is no federally regulated requirement,” certification can help to “ensure that the product isn’t a counterfeit or it’s actually effective,” said Kyle Postmus, senior manager of the Global Water Division at NSF. NSF/ANSI Standard 42 is for aesthetics, such as taste, smell and appearance (people often want to filter out traces of the disinfectant chlorine). Standard 53 focuses on safety, ensuring levels of lead or mercury, as well as some pesticides and industrial chemicals, are below the accepted limit. The certifications are for individual contaminants, and the product should specify all the contaminants it is approved to reduce. Home filters appear to work decently well for PFAS and can now be NSF/ANSI Standard 53 certified for some of those chemicals, too. In a study published in 2020, Dr. Knappe and his co-authors found that, on average, pitcher and refrigerator filters that use activated carbon reduced PFAS levels by about 50 percent. More advanced filtration systems that use a process known as reverse osmosis were over 90 percent effective, but they are much more expensive and waste a significant amount of water. Sometimes filters can cause more harm than good. Dr. Nguyen’s research revealed that if water sits in a faucet or under-sink filter for a long period of time, such as overnight, it can actually pick up more contaminants, including lead and bacteria. That’s because the water is essentially bathing in high concentrations of the contaminants that were trapped by the activated carbon. When the faucet is turned on again, the contaminant-infused water comes rushing out. As a result, Dr. Nguyen said that it is important to flush your water filter for at least 10 seconds before drinking from it. Also, be sure to change your filter regularly. Most of the experts interviewed for this article said that they used an at-home filter, but none said it was essential. Some used filters for taste issues, while others said it was a precautionary measure. “Not everybody needs them, but I can think of a lot of reasons why people might,” Dr. Cwiertny said. “What I would encourage is that people make informed decisions and know why they’re purchasing a device” — for example, for a specific taste concern or for filtering out a known contaminant . . . Stan Rowin -- The LincolnTalk mailing list. To post, send mail to Lincoln@lincolntalk.org. Browse the archives at https://pairlist9.pair.net/mailman/private/lincoln/. Change your subscription settings at https://pairlist9.pair.net/mailman/listinfo/lincoln.
