TDS, or total dissolved solids, is one of the most talked-about numbers in water purification. But what is a good TDS level, and when should you worry? This guide explains the ideal TDS range for drinking water in India and how it affects your choice of purifier.
What is TDS
TDS measures the total dissolved minerals and salts in water, expressed in parts per million (ppm) or milligrams per litre. It includes calcium, magnesium, sodium, potassium and other dissolved substances. A TDS meter gives a quick reading but does not identify which substances are present — it is a general indicator of mineral content, not a contamination test.
Ideal TDS levels for drinking water
| TDS (ppm) | Rating | What it means |
|---|---|---|
| Below 50 | Too low | Lacks minerals; may taste flat |
| 50–150 | Good | Ideal for most drinking water |
| 150–300 | Acceptable | Good taste, adequate minerals |
| 300–500 | Fair | Acceptable upper limit (BIS) |
| 500–900 | Poor | RO recommended |
| Above 900 | Unacceptable | RO essential |
The Bureau of Indian Standards (BIS) sets 500 ppm as the acceptable limit and 2,000 ppm as the permissible limit when no alternative source is available. For taste and comfort, most people prefer water in the 50–300 ppm range.
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Can TDS be too low
Yes. Water below about 50 ppm has very few minerals and can taste flat. This is why many RO purifiers include a TDS controller or mineralizer that adds back essential minerals after purification. If your purifier output is very low, consider enabling or servicing the mineralizer.
How TDS decides your purifier choice
- Below 300 ppm: A UV or UF purifier may be enough; RO is optional.
- 300–500 ppm: RO with a TDS controller gives the best balance.
- Above 500 ppm: RO is strongly recommended.
- Above 1,000 ppm: A dedicated hard-water RO unit is needed — see our best RO purifier for hard water guide.
Understanding what each technology removes helps too — read our RO vs UV vs UF comparison.
How to measure your water’s TDS
A handheld TDS meter gives an instant reading. Test both your input water and your purifier output to confirm it is working. If you are unsure how, our guide on how to check RO TDS output at home walks through the process step by step.
Our recommendation
Aim for purified drinking water in the 50–150 ppm range for the best balance of safety, taste and minerals. Test your input water first, then choose a purifier matched to that level — and verify the output regularly.
Frequently asked questions
What is the perfect TDS for drinking water?
Most experts suggest 50–150 ppm for ideal taste and mineral balance.
Is high TDS water harmful?
Very high TDS can affect taste and may indicate excess salts; RO purification reduces it to a safe level.
Is zero TDS water good?
No — extremely low TDS lacks minerals and tastes flat; a mineralizer restores balance.
Does a TDS meter detect bacteria?
No. TDS measures dissolved solids only, not microbial contamination.
What TDS is safe per BIS?
BIS sets 500 ppm as the acceptable limit and 2,000 ppm as the maximum permissible.