Water quality6 min read
What TDS should your drinking water be in Delhi NCR?
By Kanak Enterprises, who rent and service RO purifiers across Delhi NCR.
The short answer
Drinking water is considered ideal between 50 and 150 TDS, acceptable up to 300 TDS, and unpalatable above 500 TDS. India's drinking water standard sets 500 mg/l as the acceptable limit. Most Delhi NCR groundwater tests between 800 and 2000 TDS, which is well past that limit and needs reverse osmosis — no UV or candle filter reduces TDS at all.
Key takeaways
- 50–150 TDS is the ideal drinking range; up to 300 is fine; above 500 exceeds the Indian acceptable limit.
- Delhi NCR groundwater commonly tests 800–2000 TDS, and treated municipal supply 200–400 TDS.
- UV and UF filters do not reduce TDS by a single point — only reverse osmosis does.
- Very low TDS, under about 50, tastes flat and strips useful minerals, which is what a TDS controller prevents.
- A TDS reading alone does not detect bacteria or heavy metals, so it is a starting point rather than a verdict.
TDS stands for total dissolved solids: everything dissolved in your water that is not water itself, measured in milligrams per litre. Calcium and magnesium are in there, and so are chlorides, sulphates, sodium and whatever the local geology and infrastructure contribute. A ₹300 handheld meter reads it in seconds, which is why it is the number everyone quotes.
The safe range
| TDS (mg/l) | Rating | What it means in practice |
|---|---|---|
| Below 50 | Too low | Flat, insipid taste; useful minerals stripped out |
| 50–150 | Ideal | The target range — clean taste, minerals retained |
| 150–300 | Good | Perfectly drinkable, taste still fine |
| 300–500 | Acceptable | Within India's limit but noticeably hard |
| 500–900 | Poor | Past the acceptable limit; salty or bitter edge |
| Above 900 | Unacceptable | Should not be consumed untreated |
India's drinking water standard, IS 10500, sets 500 mg/l as the acceptable limit for total dissolved solids, with 2000 mg/l as the outer permissible limit where no alternative source exists. That permissible figure is a concession for water-scarce areas, not a target to aim at.
What Delhi NCR water actually tests at
The regional picture is not one number, because two homes on the same street can be on completely different sources. What your building draws from matters more than which city you are in.
| Source | Typical TDS | Where you find it |
|---|---|---|
| Treated municipal supply | 200–400 | Much of central and south Delhi on DJB supply |
| Society borewell | 700–1500 | Most Noida and Ghaziabad group housing |
| Deep borewell | 900–2000 | Greater Noida, outer Delhi, Gurugram |
| Tanker water | Highly variable | Varies week to week; test each time it changes |
What actually reduces TDS
| Stage | Reduces TDS? | What it actually does |
|---|---|---|
| Sediment / candle filter | No | Removes suspended particles and visible dirt |
| Activated carbon | No | Removes chlorine, odour and taste compounds |
| UV | No | Kills bacteria and viruses; dissolved salts pass straight through |
| UF (ultrafiltration) | No | Removes bacteria and cysts by pore size |
| RO (reverse osmosis) | Yes | The only stage that removes dissolved salts |
This is the single most common misunderstanding we encounter on service calls. A customer buys a UV purifier because the box says purifier, and is then puzzled that the water still tastes salty and the kettle still scales. UV is a disinfection stage. It has no mechanism for removing anything dissolved, and it never will.
Can TDS be too low?
Yes. An RO membrane does not distinguish between the salts you want gone and the calcium and magnesium you would rather keep, so unrestricted RO output can land under 50 TDS — water that tastes flat and has had useful minerals removed along with the problem ones.
This is what a TDS controller is for: it blends a measured amount of filtered-but-not-osmosed water back into the output, landing the result in the 60–150 range. It is also why one machine can serve both a 300 TDS municipal supply and a 1600 TDS borewell — the controller is adjusted at installation to the input you actually have. Any purifier we install is set this way and tested before we leave.
What a TDS reading will not tell you
TDS is a bulk measurement. It tells you how much is dissolved, not what. Two samples both reading 400 could be harmless dissolved calcium in one case and something you want nowhere near a glass in the other.
- It detects no bacteria or viruses at all — that is what UV and UF handle.
- It does not isolate heavy metals such as lead or arsenic, which matter at concentrations far too small to move the TDS reading.
- It says nothing about pesticides or organic contaminants.
- It is not a hardness measurement, though the two correlate loosely.
Treat TDS as the first question rather than the last. It is quick, cheap and tells you immediately whether you need reverse osmosis — which, across most of Delhi NCR, it will.
Frequently asked questions
What is the safe TDS level for drinking water in India?
IS 10500, the Indian drinking water standard, sets 500 mg/l as the acceptable limit for total dissolved solids and 2000 mg/l as the permissible limit where no alternative source exists. For taste and quality, 50–150 TDS is considered ideal and anything up to 300 is comfortably good.
What is the TDS of Delhi tap water?
It depends entirely on the source. Treated Delhi Jal Board supply typically tests 200–400 TDS. Borewell-fed colonies — much of outer Delhi and the trans-Yamuna belt — routinely test above 1200 TDS. Tanker water varies week to week, so it is worth retesting whenever the supply changes.
Does a UV water purifier reduce TDS?
No. UV disinfects by killing bacteria and viruses; it has no mechanism for removing dissolved solids, and a UV purifier will leave a 1500 TDS input at 1500 TDS. Only reverse osmosis reduces TDS.
Is 20 TDS water safe to drink?
It is safe but not ideal. Below about 50 TDS water tastes flat and has had beneficial calcium and magnesium stripped out along with the unwanted salts. A TDS controller is used to blend the output back up into the 60–150 range.
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