TDS meters are cheap and everywhere — but what do the numbers mean? This guide explains TDS, what's safe, and which treatment you actually need.
What is TDS?
Total Dissolved Solids is the total amount of dissolved minerals and salts in water, measured in mg/L (ppm). It includes calcium, magnesium, sodium, chlorides, sulphates and more. TDS alone doesn't tell you if water is safe — it doesn't measure bacteria, lead or pesticides.
BIS drinking water limits (IS 10500)
| Parameter | Acceptable limit | Permissible (no alternate source) |
|---|---|---|
| TDS | 500 mg/L | 2,000 mg/L |
| Total hardness (as CaCO₃) | 200 mg/L | 600 mg/L |
| Iron | 1.0 mg/L | No relaxation |
| Chloride | 250 mg/L | 1,000 mg/L |
| Nitrate | 45 mg/L | No relaxation |
Typical water in South Indian cities
- Bangalore: Cauvery supply is usually low TDS (often below 150). Borewell water commonly ranges from 500 to 1,500+ ppm with high hardness; some areas also show nitrate or fluoride.
- Chennai: groundwater in many areas is hard and saline; coastal pockets have high chlorides.
- Hyderabad: borewells often have high hardness and fluoride in peripheral areas.
- Coimbatore, Salem, Madurai: hard borewell water is common.
- Kochi & coastal Kerala/Karnataka: iron and acidity issues in some wells; plentiful rain for harvesting.
These are general patterns — every borewell is different. Test your own water.
Get your water tested and a purification plan recommended — free.
Get Free QuoteWhich purifier do you need?
| Your water | Recommended treatment |
|---|---|
| Cauvery / municipal, TDS < 200 | UV/UF + carbon (RO not essential) |
| Borewell, TDS 300–2,000 | RO for drinking + softener for bathing |
| High hardness only | Water softener |
| Chlorine smell / tanker water | Carbon filter |
| Iron (yellow stains) | Iron removal filter |
| Whole building | Centralized RO / filtration plant |
What's the ideal TDS for drinking?
Most people prefer drinking water between about 80 and 250 mg/L — low enough to taste clean, high enough to retain some minerals. Very low TDS (below 50) tastes flat; TDS controllers and mineral cartridges help.
Frequently Asked Questions
Is low TDS water bad?
Very low TDS water isn't harmful in itself but lacks minerals and tastes flat. Mineral or alkaline cartridges can help.
Does boiling reduce TDS?
No. Boiling kills germs but slightly increases TDS as water evaporates.
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