Reply from clearlyfiltered.comJan 9, 2025
Thank you for your feedback, Jun.
Our filters are not made to lower the TDS reading of your water. TDS meters don't actually detect all dissolved solids; they measure the electrical conductivity of water. Any electrolyte (e.g., calcium, magnesium, potassium) will increase the TDS reading, because the presence of electrolyte ions will increase the conductivity of the water. Our filters are not designed to target those electrolytes that are beneficial minerals.
TDS meters have been marketed as a way to tell if your water is clean or not, but this method of testing your water has a few issues that, without more information, make it unreliable as a measure of water quality:
• First, it only detects parts per million (ppm). Some contaminants are unhealthy in much smaller amounts like parts per billion (ppb) or even parts per trillion (ppt). It is for that very reason that we test to ppb and ppt in some cases. (You can see the full Lab Results here.)
• Second, since TDS meters generally only detect ions, a high reading assumes that all electrolytes are bad. Essential nutrients like calcium, magnesium, and potassium are electrolytes and are big parts of what make water healthy!
• Third, it will not detect other contaminants (e.g., benzene) that are not electrolytes but are still harmful to your health.
• Fourth, organic compounds, like benzene, actually make water less conductive–they increase the resistivity of the water. For example, the conductivity of water decreases when there is a big oil spill. So when organic-compound contaminants are removed conductivity increases. This means the TDS meter, which measures conductivity, will register an increase when the water is cleaner!
• Fifth, mixing with the CO2 in the air during filtration and pouring causes CO2 to dissolve in the water, which forms carbonic acid. Increases in carbonic acid in water also increases the conductivity of water, which may register as an increase in a TDS meter, even though the water did not become more contaminated.
Since the Affinity Filtration Technology used by Clearly Filtered filters is an ionic absorption process, there is a chance that the water molecules and various minerals that pass through the filter are actually electrically charged differently once they pass through the filter. We have seen TDS readings that are higher once the water actually passes through the filter, further showcasing the idea that using TDS is not an accurate means of determining water cleanliness.
As mentioned, any non-electrolyte will decrease the TDS reading. You can actually test this yourself by measuring a glass of water and then pouring sugar into the glass, stirring it, and measuring it again. As you add sugar (an organic compound), you will see that number drop. (We conducted this experiment for ourselves, which you can watch here.)
Simply put, there are many reasons that a TDS meter may show a higher reading after filtration through our products that have nothing to do with increased contaminants–and, in fact, it may even indicate that your water has less organic-compound contaminants.
For an even more in-depth explanation, you can read our TDS blog post on our website!
Please reach out if there is anything we can help with.
