What a very low TDS reading on your water purifier means for your health

A Total Dissolved Solids reading below 25 milligrams per litre on a water purifier can look unusually low, but experts say the number alone does not determine if water is safe to drink. TDS estimates dissolved substances like calcium, magnesium, sodium, and chloride, but it is not a direct measure of harmful contaminants. Dr Udit Gupta, a nephrology consultant at ISIC Multispeciality Hospital, explains that water with low TDS can still be safe, while normal readings can still hide harmful impurities. The World Health Organization does not set a health-based limit for TDS because available evidence does not show that TDS itself is harmful at typical drinking levels. Very low TDS also means the water has small amounts of minerals, but this does not automatically cause a mineral deficiency. Most calcium and magnesium come from food rather than drinking water. Claims that RO water routinely causes mineral deficiencies can be overstated for healthy people, though low-mineral water may taste flatter. Dr Gupta advises that anyone drinking highly purified water should ensure their daily diet provides enough calcium and magnesium. People with kidney disease or specific medical conditions should consult a doctor before changing their water source. A low reading is not a reason to change purifier settings right away or panic over the number alone. Regular maintenance, proper servicing, and chemical and microbiological testing matter more than chasing a specific TDS target.