How to Filter Your Water for PFAS and Other Contaminants
Once you know what contaminants are in your water, you can take knowledgeable steps to filter them out. There are many kinds of water filters. Each is best at filtering certain types of contaminants. Many systems combine different filtration methods for best results. Some models are called point of entry or whole-house systems. They filter the water before it reaches the house. There are also point of use systems. These may be mounted under the sink or on the faucet. There are also pour-through systems like the Brita pitchers and built-in refrigerator systems. Distillation is another option. At our home we use an activated carbon point-of-use system along with a counter-top distillation system and pour-through pitcher. Your tap water often has different kinds of contaminants such as pharmaceuticals, pesticides, and solvents, which is why different filter are so often combined for the best reductions.
Filter systems can also be certified, which should add confidence. The in-use effectiveness of National Sanitation Foundation (NSF)-approved faucet-mount filters for heavy metals was tested in a study in residences and commercial locations in Flint, Michigan. Without filtration, the lead concentration was 2.5 µg/L, which was twenty-times higher than the filtered water. Even in cases where the unfiltered water had lead as high as 419 µg/L, the highest filtered lead concentration was 2.9 µg/L. This is still too much. I wouldn’t want any lead in my tap water.
Scientists at Duke University and North Carolina State University say while using any filter is better than using none many of the household filters they tested are only partially effective at removing PFAS from drinking water. Some, without maintenance, increase concentrations.
They tested seventy-six point-of-use filters and thirteen point-of-entry or whole-house systems and found their effectiveness “varied widely.”
But there was good news too. All of the under-sink reverse osmosis and two-stage filters achieved near-complete removal of the PFAS chemicals. In contrast, the effectiveness of activated-carbon filters, used in many pitcher, countertop, refrigerator and faucet-mounted styles, was inconsistent and unpredictable. The whole-house systems were also widely variable and in some cases actually increased PFAS levels in the water.
They analyzed filtered water samples from homes in Chatham, Orange, Durham and Wake counties in central North Carolina and New Hanover and Brunswick counties in southeastern N.C.
Key takeaways include:
Reverse osmosis filters and two-stage filters reduced PFAS levels, including GenX, by ninety-four percent or more.
Activated-carbon filters removed seventy-three percent of PFAS contaminants, on average, but results varied greatly. In some cases, the chemicals were completely removed; in other cases they were not reduced at all. Researchers saw no clear trends between removal efficiency and filter brand, age or source water chemical levels. Changing out filters regularly is probably a very good idea, nonetheless, researchers said.
The PFAS-removal efficiency of whole-house systems using activated carbon filters varied widely. In four of the six systems tested, some PFAS levels actually increased after filtration. Because the systems remove disinfectants used in city water treatment, they can also leave home pipes susceptible to bacterial growth.
Other studies show that the five-stage iSpring RO system is a good choice. It is free standing, pre-plumbed, and comes with both booster pump and color-coded feed and discharge tubing. Except for the RO membrane, the filters and cartridges were preinstalled. Wrenches were included to install replacement membranes and filters. The iSpring RCS5T was tested over a seven-day period. All PFAS in the effluent were reduced below detection for the entire test period. The system reduced the turbidity, total organic content, and total dissolved solids, and hardness in the effluent.
The four-stage Flexeon RO System was preplumbed with filters. The Flexeon RO system was not self-supporting and did not come with a booster pump or inlet and outlet tubing, however. All PFAS in the effluent were reduced below the detection limit for the entire test. It also reduced the turbidity, organic content, dissolved solids, and hardness.
The Aquasana AQ-5200 is ANSI/NSF-certified to virtually eliminate 77 different contaminants, including lead, mercury, volatile organic compounds, pharmaceuticals, and other materials that few of its competitors catch. It’s one of a tiny handful of filters certified for PFOA and PFOS. Replacement filters cost about $60 for a set, or $120 per year on Aquasana’s recommended six-month replacement cycle. And, being barely larger than a couple of cans of soda, the system doesn’t take up a lot of valuable room under your sink.
In 2017, Minnesota released the results of a study for a faucet-mounted carbon filter made by PUR. The filter was tested for seven PFAS chemicals typically seen in groundwater in Washington County in that state. The state concluded that this low-cost filter could be used to effectively reduce PFAS contamination. Six of seven contaminants including PFOA and PFOS were removed below the reporting limits of five and ten parts per trillion, respectively. In contrast, levels of a shorter chain PFAS called PFBA were only reduced by seventy-five percent.
I would be remiss if I didn’t mention shower filters are also essential. One study found inhalation and dermal exposure from showering was equivalent to ingesting 2 liters or two quarts of water. The temperature of water has a dominant effect. A far higher percentage of volatile contaminants are released with hot shower water. Shower filters often use activated carbon, which may remove some PFAS but becomes less efficient over time. Replace regularly.
If you do everything that is necessary to properly treat your water, you will need from one to two thousand dollars. Consider that you will need to test your water before treatment as it is out of the tap at a cost of about two-hundred-fifty dollars. Once your system is installed you will need to do a retest. There’s some five-hundred dollars minimally in testing. A reverse osmosis system that fits under the sink can run from five-hundred to thousands of dollars. A shower filter is usually around fifty dollars or less. But all of these must be maintained too. We were unable to afford an under-the-sink RO system when we moved into our home but it did have a point-of-use activated carbon system. And we purchased a Waterwise distillation system plus Brita pitchers. This was something we could afford. But once we could put an under the sink model into our budget, we did that.
I feel very torn. I am talking about a lot of money that a lot of people who need these systems don’t have. I know that in some cases, there are assistance programs that supply the community with filters and/or bottled water. But even with these programs, too many families are utilizing bad water.
I wish I had a better answer for impacted families. I’ve listed public-assistance programs for water filters throughout the US in Resources.
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