Many of our customers are curious as to why our CLEAR2O® filters don’t reduce the Total Dissolved Solids, or “TDS” found in tap water. While some might expect a lengthy explanation, the answer is quite straightforward: there’s no reason to.

To understand the rationale behind this simple response, it is important to understand exactly what TDS is – and why, as a water drinker, you really don’t need to think too much about it. 

According to NSF International, an independent, accredited organization that develops public health standards and certification programs to help protect the world’s food, water, consumer products and environment, all natural water contains minerals and dissolved substances. These minerals in water can be generally measured as TDS and are primarily comprised of naturally occurring minerals - mostly inorganic salts (calcium, magnesium, potassium, sodium, bicarbonates, chlorides and sulfate). TDS can also include contaminants such as heavy metals but usually at low concentrations that represents a microscopic portion of the total TDS.

In drinking water, TDS is measured in parts per million (ppm) or mg/L. Because TDS does not present a risk to human health – there are, in fact, no studies linking TDS with any adverse health effects - the U.S. EPA has not set a mandatory TDS limit, but does suggest a maximum level of 500 ppm. At or above this level, consumers may notice deposits, colored water, staining and/or a salty taste. To be clear, these are not harmful, but rather, are noticeable aesthetics (smell, taste and color) effort when the TDS is above 500 ppm.



If you’d like a second source to make you feel better, here’s one: According to the Water Research Center, an elevated total dissolved solids (TDS) concentration is not a health hazard. The TDS concentration is a secondary drinking water standard and, therefore, is regulated because it is more of an aesthetic than a health hazard. 

As stated earlier, the main component of TDS is minerals such as calcium, potassium, manganese, iron. These minerals are essential to the human body and therefore, removing them from drinking water is not only unnecessary, it would deprive the drinker of substantial health benefits. Consider this: most bottled mineral water contains high TDS (e.g., Evian has 300 mg/l, while San Pellegrino is even higher at 850 mg/l); this can also be positive for tap water. WHO and most other institutions that regulate water quality consider values up to 600 mg/l to be entirely safe and 2,000 mg/l safe for temporary consumption in case no other water is available. (The typical sample of tap water in the U.S. contains approximately 350 mg/L of TDS.)

So now that we’ve established that TDS has no proven harmful effects, as well as the fact that “bad” ingredients make up only a small fraction of TDS in water, the next question becomes, what’s the point in measuring it? Again, we have an extremely simple measure: there is none. Despite this fact, the recent popularity of inexpensive and portable TDS meters has now made testing one’s tap water fairly common practice. However, these devices really don’t tell the whole story, and most people are led to believe that high levels of TDS are bad.

The hard truth is, TDS is not an accurate indication of water quality. Many companies that want to promote water filters for tap water use TDS as their key water quality testing method. The reason is that it’s very easy and cheap to measure. The problem is that it is not a good measure and it’s very limited in terms of water quality parameters. In fact, higher TDS readings often indicate higher levels of the trace minerals in the water which might actually be desirable.


These meters cannot directly measure the harmful elements in TDS, such as lead or arsenic - just the total amount. Specifically, they detect the conductivity directly related to the concentration of combined total dissolved solids such as minerals, salts and metals. Consequently, a TDS reading is not an indication of whether a water filter working properly to reduce these contaminants.

Which all brings us back to CLEAR2O®. The solid carbon block in our filters effective removes the harmful chemicals, disinfectants and heavy metals in one step but leaves the healthy mineral content of the water intact. Moreover, our filters are not designed to remove beneficial minerals that other filtration methods do, such as reverse osmosis or distillation method.

So, if you are testing your water with a TDS meter, know that a TDS reading the same or even higher than tap water is NOT an indication of a faulty filter, just a measure of the total dissolved solids within the water. However, if you already have a TDS meter, don’t worry. It will make a great doorstop.


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