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Please Stop Using TDS (or ppm) Testers To Evaluate Water Quality

Analies Dyjak @ Tuesday, August 23, 2016 at 2:42 am -0400
Eric Roy, Ph.D.|  Scientific Founder

***Updated on February 5, 2020***

We get quite a few questions about TDS/ppm meters (like this one) 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 & 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 in tap water, 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 or 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 or 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 US, 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, many 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 this article's header image contains deionized water with Malathion (an organophosphate pesticide) dissolved into it at 100 times higher 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 example, the water sample shown on the right hand side of this article's header image has lead 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.

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, disinfection byproducts), and things that make water taste and smell bad (chlorine, chloramine, sulfur). Hydroviv’s home water filtration systems don’t remove minerals like calcium and magnesium because there’s no reason to. 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.

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.

What If I Already Have a TDS/ppm Meter?

If you have a TDS/ppm meter (like this one), we recommend giving it to a curious child who has an interest in science! Use this opportunity to teach them about dissolved minerals by encouraging them to test different types of water (e.g. distilled, rain, river, lake) and try to explain their findings! Feel free to reach out to us at (info@hydroviv.com for educational ideas involving TDS meters).

Other Great Articles That We Think You'll Enjoy:

How EPA Regulations For Lead Are Protecting Municipalities, Not Citizens
What Science Says About Fluoride In Tap Water

Problems We Found In Milwaukee's Drinking Water

Analies Dyjak @ Thursday, July 19, 2018 at 1:31 pm -0400

Analies Dyjak  |  Policy Nerd

For Hydroviv’s assessment of Milwaukee, Wisconsin’s drinking water, we collected water quality test data from the city and the U.S. Environmental Protection Agency. We cross referenced their water quality data with toxicity studies in scientific and medical literature. The water filters that we sell at Hydroviv are optimized to filter out contaminants that are found in Milwaukee’s drinking water.

Where Does Milwaukee Source Its Drinking Water?

Milwaukee sources its drinking water from Lake Michigan. This surface water source has had a long history of pollution, including recent lawsuits involving Chromium 6 releases from an abutting steel facility.

Chromium 6 In Milwaukee’s Drinking Water

Chromium 6 is a highly toxic metal that is currently unregulated by the EPA. In recent years, Milwaukee has had a major problem with this dangerous contaminant. Chromium 6 pollution is associated with metal processing, tannery facilities, chromate production, stainless steel welding, and pigment production. This years water quality report for Milwaukee detected levels of Chromium 6 as high as 0.2 parts per billion. This concentration is 10 times higher than the concentration determined to have a negligible impact on cancer risk. EPA has acknowledged that Chromium 6 is a known human carcinogen through inhalation, but is still determining its cancer potential through ingestion of drinking water. Lung, nasal and sinus cancers are associated with Chromium 6 exposure. Ingestion of extremely high doses of chromium 6 compounds can cause acute respiratory disease, cardiovascular, gastrointestinal, hematological, hepatic, renal, and neurological distress which may result in death.

Lead In Milwaukee's Drinking Water 

In recent years, Milwaukee has had a problem with lead in drinking water. Lead enters tap water through old lead service pipes and lead-containing plumbing. 10% of sites that were tested for lead had concentrations over 7.2 parts per billion. The highest concentration detected in 2017 was 130 parts per billion, which is a whopping 8.6 times higher that the Federal Action Level of 15 parts per billion. Environmental Protection Agency, Center for Disease Control and American Academy of Pediatrics all recognize that there is no safe level of lead for children. These health and regulatory organizations are trying to reduce the allowable limit to 1 part per billion, so a concentration of 130 parts per billion is of serious concern. Additionally, these measurements may not be a true indication of your tap water if your home has lead plumbing or lead fixtures. Treated water leaving the plant may be in compliance with loose EPA standards, but could become contaminated once it enters older infrastructure. Houses built before 1986 were most likely built with lead plumbing and lead fixtures. Lead exposure can cause developmental issues, lowered IQ, and damages to the kidneys and brain.

Perfluorinated Compounds In Milwaukee's Drinking Water 

This years water quality report for Milwaukee included test data from six Perfluorinated Compounds (PFCs). Perfluorinated Compounds are associated with firefighting foam, non-stick cookware, Scotchguard and other solvents from manufacturing. The two PFCs that are the most well known and the most researched are Perfluorooctanoic acid (PFOA) which was detected at 2.1 parts per trillion and Perfluorooctane-sulfonic acid (PFOS) which was detected at 2 parts per trillion. The Agency for Toxic Substances and Disease Registry recently recommended setting a Minimum Risk Level of 20 parts per trillion for both of these chemicals. These data are preliminary and the effects to human health are still unknown. This category of chemicals are “emerging contaminants” which means they are thought to pose a potential threat to human health and the environment, but haven't yet been regulated. Perfluorinated Compounds contribute to environmental contamination largely due to the fact that they are highly resistant to degradation processes, and thus persist for many years in water, air and can enter the food chain via bioaccumulation in certain animal species.

Chloramine In Norman’s Drinking Water

While most municipalities use chlorine as the primary drinking water disinfectant, Milwaukee’s drinking water is disinfected with chloramine. Chloramine is primarily responsible for what many customers report as the “bad taste” or “pool smell” of tap water. Unlike chlorine, chloramine does not dissipate if a container of water is left in the refrigerator overnight. Most one-size-fits-all water filters use filtration media that doesn’t do a great job removing chloramine, but the filters that we design and build at Hydroviv for Milwaukee use a special filtration media that is purposefully designed to remove chloramine.

It’s important to note that only a handful of contaminants are required to be included in annual Consumer Confidence Reports, and that there are hundreds of potentially harmful unregulated contaminants that aren’t accounted for. If you’re interested in learning more about water filters that have been optimized for Milwaukee’s tap water quality, feel free to visit www.hydroviv.com to talk to a Water Nerd on our live chat feature or send us an email at hello@hydroviv.com.

Other Articles We Think You Might Enjoy:
Lead Contamination In Drinking Water
5 Things To Know About Chromium 6 In Drinking Water
Perfluorinated Compounds In Drinking Water

Problems We Found With Las Vegas Drinking Water

Analies Dyjak @ Monday, July 30, 2018 at 10:07 am -0400

**Updated July 17, 2019 to include current data

Analies Dyjak, M.A.  |  Hydroviv Research Analyst

Hydroviv's Water Nerds have updated our assessment of Las Vegas drinking water to include data from the 2019 Consumer Confidence Report. We looked at data from the Las Vegas Valley Water District, the U.S. Environmental Protection Agency (EPA), as well as from samples that we collect and analyze. Our Water Nerds then cross reference these data with toxicity studies in the scientific and medical literature, and look at upcoming regulatory changes. The custom water filters that we build for our customers in Las Vegas are optimized with this research in mind.

Source Of Las Vegas's Drinking Water

90% of Las Vegas drinking water comes from Lake Mead. Lake Mead is supplied by snow melt from the Rocky Mountains, which flows into the Colorado River. The remaining 10% comes from a groundwater aquifer under the Las Vegas Valley. This aquifer is naturally replenished by precipitation in the Spring Mountains and the Sheep Range.

Lead In Las Vegas Drinking Water

Lead enters tap water through older lead service pipes and lead-containing plumbing. When corrosion control measures put in place by the municipality fail (like what recently happened in Flint, Michigan), lead leaches into the drinking water, and can reach dangerous levels. According to the 2019 report, 10% of drinking water samples analyzed for lead in Las Vegas are over 7.5 parts per billion. Though Las Vegas water quality is currently in compliance with federal regulations, EPA and CDC both acknowledge that there is no safe level of lead, and federal regulations do not take into account levels measured at an individual tap. Homes built before 1986 are most susceptible to lead contamination. The American Academy of Pediatrics recommends that any taps used to serve children have lead levels no higher than 1 part per billion.

High Chromium 6 Levels In Las Vegas Drinking Water

Chromium 6 is a toxic metal that is not regulated by the EPA. Las Vegas’s tap water recently averaged 200 parts per trillion for chromium 6. These levels are nearly 10 times higher than the concentration determined to have a negligible impact on cancer risk.

Disinfection Byproducts (DBPs) In Las Vegas Drinking Water

DBPs are a category of emerging contaminants that form when chlorine-based disinfectants react with naturally-occurring organic matter. Although these chemicals are not currently regulated very well, the EPA has admitted that they are associated with an increased risk of bladder cancer, as well as kidney, liver, and central nervous system problems.

Still Have Questions About Las Vegas Drinking Water?

Per and Polyfluoroalkyl Substances (PFAS) are a category of unregulated contaminants that have been associated with various negative health effects, including cancer. Major cities, such as Las Vegas, are not required to test for, monitor, or even remove PFAS from drinking water. 

Hydroviv is a water filtration company that uses water quality data to optimize water filters for each customer's water. The contaminants that we list above are what we consider to be major “points of emphasis” that we use to build water filters that are built specifically for Las Vegas' water, but all of our our filters provide broad protection against a wide range of contaminants (including lead).

If you’re interested in learning more about water filters that have been optimized for Las Vegas tap water, or just have questions about water quality in general, feel free to visit www.hydroviv.com, reach out by email (hello@hydroviv.com) or through our live chat. We also frequently post water-related news on Twitter or Facebook. We pride ourselves in being a reputable source of information on water quality, and your questions will be answered by scientists, not salespeople (we don't have any salespeople).

Hydroviv NSF Certification

Hydroviv Undersink and Refrigerator Line water filters are NSF certified. If you'd like to check out our NSF listing, click here. 

Please Share This Las Vegas Drinking Water Quality Article On Social Media With Anyone You Think Would Benefit From The Information!

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Problems We Found In Omaha, Nebraska Drinking Water

Analies Dyjak @ Wednesday, August 1, 2018 at 3:22 pm -0400

Analies Dyjak, M.A.  |  Water Nerd

For Hydroviv’s assessment of Omaha, Nebraska drinking water, we collected water quality test data from the city’s Consumer Confidence Report and the U.S. Environmental Protection Agency. We cross referenced Omaha's water quality data with toxicity studies in scientific and medical literature. The water filters that we sell at Hydroviv are optimized to filter out contaminants that are found in Omaha's drinking water.

Where Does Omaha Source Its Drinking Water? 

Omaha draws its tap and drinking water from the Missouri River, Platte River, and the Dakota Sandstone aquifer.

Lead in Omaha’s Drinking Water

Lead enters tap water through older lead service pipes and lead-containing plumbing, soldered joints, and fixtures. Based on the 2017 water quality report, lead levels in Omaha ranged from 0.5 to 14.9 parts per billion. 10% of taps had levels over 6.4 parts per billion, which is barely in compliance with the loose EPA standard of 15 parts per billion. However, if you were to ask toxicologists, pediatricians, or the CDC they would all tell you that there is no safe minimum level of lead. Lead is a neurotoxin that can have serious developmental effects on children.

Arsenic in Omaha’s Drinking Water

Arsenic is a heavy metal that typically leaches into groundwater as surrounding bedrock naturally weathers overtime. According to the most recent data, Arsenic concentrations ranged from 1 to 3.93 parts per billion in Omaha drinking water. EPA set a Maximum Contaminant Level of 10 parts per billion for Arsenic, but several health and regulatory agencies believe this level should be reduced to 1 or even 0 parts per billion. Arsenic is a toxic substance that is linked to a long list of health problems in humans. For example, arsenic can cause a number of different cancers (e.g. skin, bladder, lung, liver, prostate), as well as create non-cancerous problems with cardiovascular (heart/blood vessels), pulmonary (lungs), immune, neurological (brain), and endocrine (e.g. diabetes) systems. Hydroviv recommends purchasing a filter that is optimized to remove Arsenic from your drinking water, especially if you’re serviced by a private well.

Disinfection By-Products in Omaha’s Drinking Water

When water treatment facilities sanitize the water with chemicals such as chlorine, different contaminants can be created. These types of contaminants are called Disinfectant by products or DBPs. They are split into two categories: Total Trihalomethanes (TTHMs) and Haloacetic Acids-5 (HAA5). Concentrations of TTHMs averaged 40.2 parts per billion but were detected as high as 66.5 parts per billion. HAA5 concentrations averaged 19.6 parts per billion but were detected as high as 37.6 parts per billion. For a bit of perspective, EPA set a Maximum Contamination Level of 80 parts per billion for TTHMs and 60 parts per billion for HAA5.

Chromium 6 In Omaha’s Drinking Water

Chromium 6 is an unregulated toxic metal that's associated with metal processing, tannery facilities, chromate production, stainless steel welding, and pigment production. Concentrations of Chromium 6 were found to be ranging from 130 parts per trillion to 1400 parts per trillion. These levels are nearly 70 times higher than the concentration determined to have a negligible impact on cancer risk. EPA has acknowledged that Chromium 6 is a known human carcinogen through inhalation, but is still determining its cancer potential through ingestion of drinking water. Lung, nasal and sinus cancers are associated with Chromium 6 exposure. Ingestion of extremely high doses of chromium 6 compounds can cause acute respiratory disease, cardiovascular, gastrointestinal, hematological, hepatic, renal, and neurological distress which may result in death.

Synthetic Organic Contaminants in Omaha's Drinking Water

Di(2-ethylhexyl)phthalate was also detected in Omaha's drinking water. This chemical is known for its ability to make plastic flexible. A toxicology report has shown that this chemical is known to cause reproductive problems in young males, stomach pains, and is labeled as a probable carcinogen. EPA set a Maximum Contaminant Level of 6 parts per billion for this contaminant. The Omaha water quality problem report detected concentrations of these chemicals ranging from less than 2 parts per billion to 3.11 parts per billion.

Other Articles We Think You Might Enjoy:
Lead Contamination In Drinking Water
Disinfection Byproducts In Drinking Water: What You Need To Know
5 Things To Know About Arsenic In Drinking Water


Problems We Found With Columbus, Ohio's Drinking Water

Analies Dyjak @ Wednesday, August 1, 2018 at 2:56 pm -0400

Ernesto Esquivel  |  Water Nerd

For Hydroviv’s assessment of Columbus drinking water, we collected water quality test data from the city’s Consumer Confidence Report and the U.S. Environmental Protection Agency. We cross referenced Columbus water quality data with toxicity studies in scientific and medical literature. The water filters that we sell at Hydroviv are optimized to filter out contaminants that are found in Columbus drinking water.

Where Does Columbus Source Its Drinking Water?

Columbus sources its drinking water from the Scioto River, Big Walnut Creek, and groundwater from the Scioto River Valley. The city is serviced by three water treatment plants that each take care of a certain area of the city. The three plants are the Dublin Road treatment plant (DRWP), the Hap Cremean Water Plant (HCWP), and the Parsons Avenue Water Plant (PAWP).

Chromium 6 In Columbus Drinking Water

Chromium 6 is a highly toxic metal that is currently unregulated by the EPA. In recent years, Columbus city water has had a problem with this dangerous contaminant. Chromium 6 pollution is associated with metal processing, tannery facilities, chromate production, stainless steel welding, and pigment production. In this years water quality report, concentrations of Chromium 6 were detected as high as 0.35 parts per billion in certain groundwater sources. These levels are 17 times higher than the concentration determined to have a negligible impact on cancer risk. EPA has acknowledged that Chromium 6 is a known human carcinogen through inhalation, but is still determining its cancer potential through ingestion of drinking water. Lung, nasal and sinus cancers are associated with Chromium 6 exposure. Ingestion of extremely high doses of chromium 6 compounds can cause acute respiratory disease, cardiovascular, gastrointestinal, hematological, hepatic, renal, and neurological distress which may result in death.

Disinfection Byproducts In Columbus Drinking Water

Columbus city water problems also includes high concentrations of disinfection byproducts or DBPs. DBPs are formed when chlorine-based disinfectants react with organic matter. They are split into two categories: Total Trihalomethanes (TTHMs) and Haloacetic Acids-5 (HAA5). Concentrations of HAA5 averaged 29.4 parts per billion at DRWP, 45.3 parts per billion at HCWP, and 8.4 parts per billion at PAWP. Concentrations of TTHMs averaged 40.2 parts per billion at DRWP, 53 parts per billion at HCWP, and 34.1 parts per billion in PAWP. For a bit of perspective, EPA’s Maximum Contaminant Level for HAA5 is 60 parts per billion and 80 parts per billion for TTHMs. Disinfection Byproducts are a category of emerging contaminants which means they have been detected in drinking water but the risk to human health is unknown. Regulatory agencies have very little knowledge about the adverse health effects of DBPs, and their toxicity. EPA has stated that they have been linked to an increased risk of bladder cancer, as well as kidney, liver, and central nervous system problems.

It’s important to note that only a handful of contaminants are required to be included in annual Consumer Confidence Reports, and that there are hundreds of potentially harmful unregulated contaminants that aren’t accounted for. If you’re interested in learning more about water filters that have been optimized for Columbus tap water quality, feel free to visit www.hydroviv.com to talk to a Water Nerd on our live chat feature or send us an email at hello@hydroviv.com.

Other Articles We Think You Might Enjoy:
5 Things You Should Know About Chromium 6
Disinfection Byproducts In Drinking Water: What You Need To Know