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The Truth about Berkey® Water & TDS Meters

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One of the most common questions we have been asked in the last 15 years has to do with “Why does my Berkey water have a high TDS reading? Doesn’t that mean that the filters aren’t working?”

That’s a great question, so let’s talk about it!

First, just what is a TDS meter and what does it do?

A TDS meter measures “total dissolved solids” in water. Total dissolved solids include minerals, heavy metals, and salts, or the total amount of charged ionic matter, both organic and inorganic. While a TDS reading can indicate one of many valuable characteristics of the quality of your water, it is not an accurate measure of actual water purity. It is only a measure of the total dissolved solids in the water. It is not a measure of the overall characteristics of water such as:

  • contaminant load (biological, chemical, pharmaceutical, etc.)
  • color
  • hardness
  • odor
  • pH
  • taste
  • turbidity

Often, customers will fall for the clever marketing ploy of companies that provide a TDS meter as a way of convincing consumers that a lower TDS count equates to “pure water”. In the case of when our customers put tap water through their Black Berkey® elements, and the before and after TDS results read close to or exactly the same, they wonder, “Have I been scammed?” or “I just paid $300 to drink tap water?!”

The false positive is likely due to  some harmless carbon dust or “fines” from the filters have made it into the bottom chamber and into the test results. This is perfectly normal and fine, no need for alarm. It often happens with brand new filters, or after filters have been scrubbed and primed. It could take a few cycles for the carbon fines to reduce, but it is common for fines to be transferred to the lower chamber for the life of the filters and the amount can vary.

The premium-grade carbon and other proprietary ingredients are harmless and will uneventfully pass through the body. They do not cross any blood/brain or similar barriers within the body and will be eliminated through normal body waste functions.

Second, not all total dissolved solids are created equal. In fact, the Black Berkey® purification elements are specifically designed not to remove beneficial ionic minerals from fresh water; these are minerals that countless individuals all over the world see as necessary for optimum health. Water as it is found naturally all over the earth has minerals.

Here is a list of both major minerals (recommended dietary consumption > 100mg/day) and trace minerals (recommended dietary consumption < 100mg/day) that the Berkey® does not remove, keep in mind that hundreds of millions of people consume these same exact minerals in supplements every day:


The Black Berkey® elements are designed, however, to reduce and remove biological & chemical contaminants, and heavy metals and sedimentary minerals (aluminum, iron oxide, etc.). Below are heavy metals that the Black Berkey® purification elements have been tested to remove from water:

Aluminum, Antimony, Arsenic, Beryllium, Cadmium, Chromium, Copper, Iron, Lead, Manganese, Mercury, Nickel, Selenium, Zinc.

From NMCL:

“TDS meter does not measure the amount of biological and chemical contaminants. The important thing is to not simply rely on a TDS meter for your measure of whether your water is good. You can have low TDS count water that has harmful bacteria in it. You can have high TDS count water that is perfectly safe (e.g. – pure, un-polluted ocean saltwater…albeit, you wouldn’t drink it, but that’s only because the mineral is salt). Thus, make sure you know what your TDS meter is actually telling you.”


– USA Berkey Filters