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A TDS reading of zero does not mean your water is pure and uncontaminated by other substances. It means there is little to no movement of charged ions between the electrodes of the probe.
As Randy Holmes-Farley discusses in his article "What is TDS?", the term TDS (Total Dissolved Solids) is really a misnomer. The more correct term would be "Total Charged Ions". The article is worth reading. Here's an excerpt of one of the key points:
As conductivity meters in disguise, TDS meters will only detect mobile charged ions. They will not detect any neutral (uncharged) compounds. Such compounds include sugar, alcohol, many organics (including many pesticides and their residues), and unionized forms of silica, ammonia, and carbon dioxide. These meters also do not detect macroscopic particulates, as those are too large to move in the electric fields applied. So if you see "rusty" looking water from iron oxide particulates, that won't be measured. Neither will anything else that makes the water look cloudy. Bacteria and viruses also won't be detected.
Check out all the uncharged and large stuff that TDS meters won't notice. Seem to me there could be a significant percentage of mystery tank issues that are in reality due to contaminated water that was assumed to be pure based on filtration at a zero TDS standard.
As Randy Holmes-Farley discusses in his article "What is TDS?", the term TDS (Total Dissolved Solids) is really a misnomer. The more correct term would be "Total Charged Ions". The article is worth reading. Here's an excerpt of one of the key points:
As conductivity meters in disguise, TDS meters will only detect mobile charged ions. They will not detect any neutral (uncharged) compounds. Such compounds include sugar, alcohol, many organics (including many pesticides and their residues), and unionized forms of silica, ammonia, and carbon dioxide. These meters also do not detect macroscopic particulates, as those are too large to move in the electric fields applied. So if you see "rusty" looking water from iron oxide particulates, that won't be measured. Neither will anything else that makes the water look cloudy. Bacteria and viruses also won't be detected.
Check out all the uncharged and large stuff that TDS meters won't notice. Seem to me there could be a significant percentage of mystery tank issues that are in reality due to contaminated water that was assumed to be pure based on filtration at a zero TDS standard.
