Water Quality InformationWritten By Actual ExpertsRSS
Eric Roy, PhD & Analies Dyjak, M.A.The Red Dye Test is a visual demonstration used in marketing materials by various water filtration companies. In this demonstration, red food coloring is added to water and passed through a filter, where it comes out clear. Oftentimes this demonstration is done in a “side by side” manner against another water filter that does not remove the red coloring from the water. This demonstration suggests to the consumer that:
If a water filter can remove red dye, it’s also removing dangerous contaminants. In scientific terms, they’re suggesting that red dye is a “proxy” or “surrogate” for dangerous contaminants.
Water filters that do not remove the red color are not as effective as water filters that do remove red food coloring.
Is Red Food Coloring a Representative Proxy or Surrogate for Contaminants in Drinking Water?
Absolutely not. Identifying a representative proxy/surrogate requires that a credible testing body (e.g NSF/ANSI) has actually done experiments to validate it. An example of a representative surrogate test is NSF/ANSI Standard 53 for VOCs, where the certifying bodies have shown (through testing) that chloroform is an effective surrogate for roughly 50 VOCs. No such testing has been done (or to our knowledge attempted) for red food coloring. It goes without saying, if the visual removal of red food coloring was a representative surrogate for water filter performance, credible water filter companies would not be spending millions of dollars on research, development, testing, and evaluation.
Are Water Filters That Do Not Remove Red Food Coloring Less Effective At Removing Dangerous Chemicals?
Absolutely not. For example, one of the brands that prominently markets using the red dye test was part of a water filter evaluation study conducted by Duke and NC State University, and failed miserably. Conversely, various products that do not remove red food coloring (Hydroviv’s included) were effective in filtering “hard-to-filter” PFAS from the challenge solutions. So while the brand effectively removes food-safe red dye, it isn’t able to remove PFAS. In fact, higher levels of PFAS were detected in the filtered water because the filtration media was likely oversaturated. In short, red dye is extremely easy to remove and is not an actual indication of filter performance or contaminant removal.
Is There a Quick and Easy Way To See if My Filter is Working?
While we wish there was an at-home test that could determine if your filter is doing its job, that unfortunately isn’t the case. Every home in America would test their water on a regular basis if at-home test kits provided actual information about water quality. If you want to test for contaminants, you’ll need to send a water sample to an accredited laboratory and test for a range of contaminants. This can cost thousands of dollars and doesn’t provide immediate results. The best way to ensure that you’re using an effective product is to buy products from companies that use third party testing & certifications.
Summary: The Red Dye Test is a Marketing Gimmick
The red dye test tells us almost nothing about filtration performance and shouldn’t be used as a proxy/surrogate for harmful contaminants.Other Articles Recommended For You:
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Eric Roy, Ph.D, | Scientific Founder
***Updated on March 22, 2022***
We get quite a few questions about TDS/ppm meters and TDS measurements. While we love when people take steps to learn more about their water, some people (including journalists from reputable publications - Example #1 and Example #2) have used TDS/ppm meters to draw false conclusions about water quality, which incited fear in people already in the midst of a terrible water quality crisis. In this article, we answer the questions that we get asked the most about TDS measurements and TDS meters. If you're curious about water filters that address meaningful contaminants, check out this recent water filter study by Duke/NC State.
What is TDS? What Does a TDS/ppm Meter Measure?
TDS stands for Total Dissolved Solids which is related to the total charged mineral content of water. TDS can be easily determined by measuring the conductivity of a water sample, which is exactly what inexpensive TDS probes do. TDS meters typically display the total amount of dissolved solids in parts per million of ppm. If you start with deionized water (which has a TDS of zero), and expose it to minerals that contain sodium, calcium, and magnesium... the water's TDS of ppm rises. This is why there's no such thing as deionized water in nature. Depending on a region's geology, natural TDS/ppm levels can vary across the U.S., and this variability has nothing to do with the water quality (except in extreme cases when the water is too salty to drink).
What Does a TDS/ppm Meter NOT Measure?
Because TDS/ppm is an aggregate measure of charged compounds in water, uncharged things like motor oil, gasoline, pharmaceuticals, and pesticides do not contribute to a TDS/ppm measurement. Most relevant to current nationwide water quality problems, TDS/ppm meters do not detect PFAS in drinking water. For example, the glass on the left in the picture above contains deionized water with Malathion (an organophosphate pesticide) dissolved into it at 100 times high concentration than allowed by the EPA for drinking water, and the TDS/ppm probe reads 000.Even though these toxic metals are charged when dissolved in water, a TDS/ppm meter does not give meaningful information about their presence or concentration in water. There are two main reasons for this:
A TDS/ppm meter is a nonselective measurement and cannot differentiate among different ions. A more sophisticated piece of equipment is needed to perform those types of measurements. The value of 184 that was measured using a TDS meter in a prominent Huffington Post Article was not the lead concentration... it was the water's natural TDS level (which is dominated by minerals like calcium, magnesium, and sodium).
A TDS tester is not sensitive enough to measure toxic levels of lead, chromium 6, or arsenic, even if they are present in a sample. This is because the reading displayed on an inexpensive TDS meter is in parts per million, while things like lead, chromium 6, and arsenic are toxic at part per billion concentrations (1000 times lower). Using a TDS meter to measure ppb lead concentrations in tap water is like trying to use a car's odometer to measure a child's height... it's the wrong tool for the job. For example, the water sample shown on the right hand side of this article's header image has levels that are 100x the EPA limit, and the TDS reading teetered between 000 and 001.
To reiterate: meaningful lead and arsenic measurements cannot be made using a TDS/ppm meter (or any other handheld device). They must be measured by trained staff in analytical laboratories that use much more sophisticated scientific equipment. Hydroviv Undersink filters are NSF/ANSI 53 certified to remove lead from drinking water.
Should I Buy a TDS/ppm Meter To Test My Drinking Water For High TDS Levels?
No. There is absolutely no reason to drink low TDS/ppm or deionized water. If you are concerned about water quality, put the money toward the purchase of an effective drinking water filter that removes harmful contaminants from your water.
When is a TDS Meter Helpful?
Some types of water filters (e.g. distiller, Reverse Osmosis, high performance pitchers, etc) work by deionizing the water, and for these specific products, a TDS meter is a great tool to test to make sure the product's core technology is functioning properly (similar to how your vehicle's check engine light lets you know that the car's systems are working properly).
Do Hydroviv Filters Lower TDS/ppm?
No. Hydroviv's filters selectively filter harmful things from your water (like lead, chromium 6, pesticides, pharmaceuticals, petroleum products, and disinfection byproducts), and things that make water taste and smell bad (chlorine, chloramines, and sulfur). Hydroviv's home water filtration systems don't remove minerals like calcium and magnesium. In fact, we use some types of filtration media that actually add minerals to the water, so TDS/ppm levels in water filtered through a Hydroviv system are sometimes slightly higher than unfiltered water.
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Analies Dyjak, M.A. | Head of Policy and Perspectives
The city of Eau Claire, Wisconsin is in the national spotlight for PFAS contamination in drinking water. The city’s water utility provider shut down half of it's wells due to unsafe levels of PFAS earlier this month. PFAS are a category of harmful contaminants that are known to cause cancer and other dangerous health impacts.
Where Is The PFAS Pollution Coming From?
PFAS pollution has contaminated half of the 16 drinking water wells in the city of Eau Claire. The Wisconsin Department of Natural Resources (DNR) believes that the contamination originated from the Chippewa Valley Regional Airport in Eau Claire. Airports and military bases are known to be a main source of PFAS contamination due to the excessive use of firefighting foam during training activities. PFAS are a key ingredient in firefighting foam because of their ability to act as a surfactant and suppress fire. You might see PFAS referred to as Aqueous Fire Fighting Foam or AFFF in this particular context. Camp Lejeune, McClellan Air Force Base, Pease Air Force Base, and Gerald R. Ford International Airport are some of the more well known incidences of AFFF contamination. There are however several other sources of PFAS that could be contributing to the contamination, including nearby PFAS manufacturing and processing facilities.
How Is Eau Claire Mitigating The Problem?
One of the most difficult hurdles faced by municipalities across the country is what to do with the PFAS once its contaminated a water supply. The Utilities Manager for the City of Eau Claire stated that they’re currently emptying out their wells and dumping contaminated water into “absorption ponds.” These ponds are a temporary solution and are problematic in their own way. PFAS can still seep from the absorption ponds into surrounding soil and groundwater. The utilities manager said in a recent interview that the absorption ponds are located in an area that “should not impact municipal drinking water.” The absorption ponds also don’t take into consideration the health of aquatic species and other organisms in that habitat. PFAS are known to bioaccumulate in fish, which could indirectly affect humans throughout the food chain.
City officials made the decision not to provide bottled water to its residents, and continue to allow them to drink the contaminated water on the grounds that it’s “under the DNR hazard index level” of 20 parts per trillion. Proactive sampling occurred in 2020, which found that Eau Claire wells had detectable levels of PFAS. In 2021 when the hazard index was introduced in the state of Wisconsin, the utility department determined that PFAS were then problematic.
What’s Next For The City of Eau Claire?
There are currently no mitigation plans and several unknowns regarding the next steps for the city of Eau Claire. State and local officials are still unsure of the size of the plume, the direction of the plume, and the levels that they are dealing with. The City of Eau Claire has hired an engineering firm to assist with answering some of these questions as well as a cost estimate for future action. The utilities manager did however say that since removing PFAS-contaminated water, PFAS levels had decreased in 5 of the city wells.
Once PFAS are in a water supply it’s nearly impossible to eliminate all of the contamination. Water treatment plants will simply focus on water that’s actually being consumed by members of a community, which includes purchasing proper filtration technologies. It’s important to note that Eau Claire is not the only municipality that has taken water sources “offline” due to PFAS contamination. The community of Bethany Crest, Delaware was told to only use bottled water for drinking and cooking due to “concerning levels” or PFAS. Many municipalities are testing for PFAS for the very first time, so there’s no way of knowing how long PFAS has been a problem in either of these communities.
The utilities manager in an interview with Wisconsin Public Radio stated that “the city of Eau Claire’s water is safe and always has been.” We’ve seen similar statements from public officials in other states when their water was in fact not safe at all. The mayor of Newark, NJ made a similar statement about lead levels that were almost two times higher than the federal limit, claiming that Newark’s water was not only safe, but “some of the best in New Jersey.” We suggest first taking a look at this Environmental Working Group (EWG) map to see if PFAS have been detected in your area. You may also consider purchasing a filter that removes PFAS contaminants.Other Articles We Think You Would Enjoy:
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