TDS Level in Drinking Water: What Is Safe? (India Guide)
Your TDS meter just beeped 780 ppm. Is that dangerous? Should you panic? Or is 150 ppm actually too low? TDS (Total Dissolved Solids) is one of the most misunderstood water quality parameters — and marketers have made the confusion worse. Here is what the science and Indian standards actually say.
 TDS Level Chart for Drinking Water Color-coded chart showing TDS ranges from 0-2000 ppm with safety zones marked from excellent to dangerous |
What Is TDS?
Total Dissolved Solids (TDS) is a measurement of all inorganic and organic substances dissolved in water, expressed in parts per million (ppm) or milligrams per litre (mg/L). These dissolved substances include:
- Minerals: calcium, magnesium, potassium, sodium (generally beneficial)
- Heavy metals: lead, arsenic, mercury, chromium (harmful at elevated levels)
- Salts: chlorides, sulfates, nitrates (harmful in excess)
- Industrial contaminants: pesticides, solvents (harmful)
Here is the crucial insight: TDS tells you HOW MUCH is dissolved, but not WHAT is dissolved. A high TDS reading could mean mineral-rich spring water (mostly harmless) or heavily contaminated industrial water (dangerous). Context is everything.
TDS Standards for Drinking Water in India
| Standard Body | Maximum Acceptable | Desirable Limit | Status |
| BIS (IS 10500:2012) | 500 ppm | 300 ppm | Indian national standard |
| WHO | 600 ppm (guideline) | 300 ppm (recommended) | International guideline |
| USEPA | 500 ppm | No specific guideline | US standard |
| EU Drinking Water Directive | No mandatory limit | Below 500 ppm recommended | EU guideline |
TDS Level Categories: What Each Range Means
| TDS Range (ppm) | Category | Taste Profile | Health Impact | Action Needed |
| 0–50 | Extremely Low | Flat, bland | Mineral deficiency risk with long-term use | Add mineraliser; use only with RO + mineraliser |
| 50–150 | Excellent | Clean, fresh | Optimal for health | Ideal purified water range |
| 150–300 | Good | Slightly mineral | No concerns; beneficial minerals present | Good range; no action needed |
| 300–500 | Acceptable | Noticeable taste | Generally safe; monitor specific contaminants | Consider RO if borewell or industrial area |
| 500–900 | Poor | Salty/bitter notes | May cause scale deposits; monitor for metals | RO purification strongly recommended |
| 900–1200 | Very Poor | Distinctly unpleasant | Health risks with prolonged exposure | Do not drink without RO purification |
| Above 1200 | Dangerous | Undrinkable | Serious health risks; likely toxic contaminants | Immediate water treatment or alternative source |
How to Measure TDS at Home
A TDS meter is a small digital device that measures electrical conductivity of water (dissolved ions conduct electricity), then converts this to a TDS reading. They are available online for Rs 200–800.
How to Use a TDS Meter
- Remove cap and turn meter on
- Dip the probe end 2–3 cm into the water sample
- Gently stir for 10 seconds to stabilise reading
- Read the display (most show ppm directly)
- Multiply by temperature compensation factor if needed (press TEMP button)
- Rinse probe with distilled water after use
| Pro Tip: Test Multiple Points |
| Test directly from source tap (before purifier) |
| Test from purifier output to check if your RO is working |
| Test from storage tank to monitor water quality over time |
| A good RO should reduce TDS by 85-95% — if not, membrane may need replacement |
 How to Use a TDS Meter Step by Step Photo sequence showing correct TDS meter usage in different water samples including tap and purified water |
TDS by City: What to Expect Across India
| City / Region | Typical Source TDS | Common Issues |
| Delhi NCR | 300–600 ppm (municipal), 800–1500 (borewell) | Arsenic traces, high hardness |
| Mumbai | 100–250 ppm | Bacterial, chlorine; relatively low TDS |
| Bangalore | 150–350 ppm | Moderate; varies by area |
| Chennai | 400–800 ppm | High TDS from coastal aquifers, hardness |
| Kolkata | 200–400 ppm | Arsenic risk in East zone, bacterial |
| Rajasthan (rural) | 800–2000+ ppm | Fluoride contamination, extremely high TDS |
| Punjab (rural) | 300–800 ppm | Nitrates from agriculture, arsenic risk |
| Coastal Karnataka | 250–600 ppm | Saline intrusion near coast |
The Zero TDS Myth
Many salespeople and some brands promote ‘zero TDS purified water’ as the healthiest option. This is misleading. WHO and research scientists have noted that long-term consumption of demineralised water may:
- Increase risk of magnesium and calcium deficiency
- Lead to higher uptake of heavy metals (demineralised water is more aggressive in leaching)
- Cause electrolyte imbalance in some populations
The ideal output TDS from a home RO purifier is 75–150 ppm, achieved via a TDS controller or mineraliser cartridge. This retains essential minerals while removing harmful dissolved solids.
 Mineral Content vs TDS Range Infographic showing which essential minerals are present at different TDS levels and what an ideal mineralised water profile looks like |
Frequently Asked Questions (FAQ)
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What is the ideal TDS for drinking water in India?
The BIS standard (IS 10500:2012) recommends a desirable TDS limit of 300 ppm with an acceptable maximum of 500 ppm. Most water quality experts and the WHO suggest 100–300 ppm as the optimal range for daily drinking water. After RO purification, an output of 75–150 ppm with mineraliser is ideal.
Is 400 ppm TDS water safe to drink?
400 ppm TDS is within the BIS acceptable limit of 500 ppm and is generally safe for drinking. However, the safety depends on what is contributing to that TDS. If it is calcium and magnesium (natural hardness), it is safer than if fluoride, arsenic, or industrial chemicals are present. Always verify the source before drinking.
My RO output TDS is 20 ppm. Is that too low?
Yes, 20 ppm is very low and indicates that your RO is removing nearly all minerals. This is technically ‘over-purified’ water. Long-term consumption without a mineraliser may lead to mineral intake reduction. Ensure your purifier has a functional mineraliser cartridge and replace it as per the maintenance schedule (usually every 6–12 months).
Can I drink water with TDS of 1000 ppm?
No. Water with TDS above 600–700 ppm has a noticeably unpleasant taste and may pose health risks depending on what contributes to the high TDS. At 1000 ppm, you should not consume this water regularly without proper RO purification. Use an RO purifier that can reduce it to below 150 ppm.