Water quality · India · Karnataka & Tamil Nadu
What is a safe TDS level for drinking water? (BIS limits explained)
“Safe TDS” is one of the most-searched water questions in India, and the honest answer has two parts: what the standard allows, and what actually tastes and works well in your home. This page keeps both grounded in BIS IS 10500 and WHO guidance, then points you to test your own supply.
Short answer
India's drinking-water standard, BIS IS 10500, sets an acceptable limit for total dissolved solids (TDS) of 500 mg/L (milligrams per litre, the same as ppm). It allows a higher permissible limit of 2000 mg/Lonly “in the absence of an alternate source.” The World Health Organization does not set a strict health-based TDS limit; instead it describes palatability tiers, where water below roughly 300 mg/L is considered excellent-tasting and above about 1200 mg/L becomes unacceptable to most people. So a practical safe-and-pleasant target for most homes is under 500 mg/L, ideally under 300.
Last verified: July 2026. Sources: BIS IS 10500 (Drinking Water Specification) and WHO Guidelines for Drinking-water Quality. Treat the exact thresholds as figures to confirm against the current standard.
TDS ranges at a glance
The table below is a plain-English guide that maps TDS bands to taste and usability, aligned to the BIS acceptable (500) and permissible (2000) limits and to WHO's palatability tiers. Treat the band edges as guidance, not hard cut-offs — real supply varies, and TDS is only one signal.
| TDS (mg/L) | Rating | What it means |
|---|---|---|
| Below 300 mg/L | Excellent | Widely considered the best-tasting range; comfortably within BIS acceptable. |
| 300–600 mg/L | Good | Still within or near the BIS acceptable band; fine for most homes. |
| 600–900 mg/L | Fair | Above BIS acceptable (500) but under the permissible ceiling; taste and hardness usually noticeable. |
| 900–1200 mg/L | Poor | Hard/salty taste common; many homes treat at this level. |
| 1200–2000 mg/L | Unacceptable for regular use | Only 'permissible' where no alternate source exists; treatment strongly advised. |
Bands are guidance ranges synthesised from the BIS acceptable / permissible limits and WHO palatability tiers; exact WHO tier boundaries should be confirmed against the current guideline.
What TDS is — and what it isn't
Total dissolved solids is the combined weight of everything dissolved in your water: calcium, magnesium, sodium, chlorides, sulphates, bicarbonates and other inorganic salts, plus small amounts of organic matter. A handheld TDS meter estimates it by measuring electrical conductivity, which is why it's cheap and instant.
- TDS measures dissolved minerals, not pathogens. It cannot tell you whether water carries bacteria, viruses or specific contaminants like nitrate, fluoride, arsenic or lead. Water can have a comfortable TDS reading and still be microbially unsafe.
- Low TDS is not automatically “pure.” A very low reading just means few dissolved salts. It says nothing about germs or dissolved gases, and extremely low TDS can taste flat and contribute fewer beneficial minerals.
- High TDS is a flag, not a verdict.It usually points to hardness or salinity worth addressing for taste and appliance life, and it's a good prompt to run a fuller test — but a lab test for specific parameters is what confirms safety.
For how RainbowHome weighs these signals rather than pushing a single product, see how we rank and our methodology.
High TDS in Bengaluru borewells and Chennai supply
TDS is very local. In Bengaluru, borewell-dependent peripheral and IT-corridor zones — Whitefield, Bellandur, Sarjapur Road, Electronic City, Yelahanka — commonly run harder and higher on TDS, often from a few hundred mg/L up past 1000 mg/L depending on the individual borehole and depth. Areas on Cauvery supply through BWSSB generally run lower. Because two boreholes on the same street can differ, treat any area figure as directional.
In Chennai, piped supply from Chennai Metrowater is typically moderate, but many homes and apartments supplement with borewell or tanker water, which can push TDS and salinity up — coastal and over-extracted pockets see the highest readings. Again, the number that matters is the one from your tap.
Last verified: July 2026. Local supply context: BWSSB (Bengaluru) and Chennai Metrowater. Area TDS ranges are directional signals from public groundwater studies, not a measurement of any specific home.
What to do about it: test first, then decide
The sequence that saves money is simple: measure your own water, then match the treatment to the problem rather than buying the biggest purifier on the shelf.
- Test your supply.A TDS meter gives you a number in seconds; a lab test adds the safety parameters TDS can't see. Start with our free water-quality check or read how to test water quality at home.
- High TDS / brackish water → consider RO. Reverse osmosis is the usual answer when dissolved salts are the problem, because it actually removes them and lowers TDS.
- Hardness (scale, poor lather) → a softener may fit. A softener swaps hardness ions but does not meaningfully lower TDS, so it solves scale, not salinity. See RO vs water softener for Bengaluru to tell them apart.
- Compare full options. Once you know your numbers, weigh purifier and filtration choices at water filtration options.
Find your own TDS in about 30 seconds
Get a read on your specific home, then see whether you need treatment — and which kind — without a sales call.
Safe TDS for drinking water — frequently asked
What TDS level is safe for drinking water in India?
Under BIS IS 10500, up to 500 mg/L (ppm) of total dissolved solids is the acceptable limit for drinking water. Between 500 and 2000 mg/L is treated as permissible only where no better source is available. Above 2000 mg/L is generally not recommended for drinking without treatment. In practice, most people find water below about 300 mg/L tastes best.
What is the BIS acceptable limit for TDS in drinking water?
BIS IS 10500 sets the acceptable limit for total dissolved solids at 500 mg/L. The same standard allows a higher permissible limit of 2000 mg/L in the absence of an alternate source. Acceptable means desirable for regular drinking; permissible means tolerable only when nothing better is available. Confirm the current figures on the BIS standard before quoting them.
Is low TDS water bad for you?
Very low TDS water (roughly below 50 mg/L) can taste flat because some of the taste of water comes from dissolved minerals, and it contributes fewer minerals like calcium and magnesium. It is not dangerous for a normal diet, but many RO systems add a mineraliser stage to lift very low TDS back into a more palatable range. Low TDS on its own does not prove water is safe — TDS says nothing about bacteria.
Does high TDS mean water is unsafe to drink?
Not by itself. TDS measures the total dissolved inorganic salts and minerals, not pathogens or specific toxins. High TDS often signals hardness or salinity that affects taste and appliances, and can flag the need for a fuller test, but a lab test for specific parameters (nitrate, fluoride, heavy metals, bacteria) is what actually determines safety.
What TDS is typical for Bengaluru borewell water?
Borewell water in Bengaluru's peripheral and IT-corridor zones (Whitefield, Bellandur, Sarjapur Road, Electronic City) commonly runs on the higher side and can sit anywhere from a few hundred to well over 1000 mg/L depending on the borehole. Cauvery-supplied areas run lower. These are directional ranges, not a reading for your specific home — the only way to know is to test.
Does an RO purifier reduce TDS?
Yes. Reverse osmosis pushes water through a semi-permeable membrane that removes most dissolved salts, so it lowers TDS substantially and is the usual choice for high-TDS or brackish supply. A water softener, by contrast, mainly swaps hardness ions and does not meaningfully lower TDS, so the two solve different problems.
Last verified: July 2026. Standards and thresholds cited from BIS IS 10500 Drinking Water Specification and the WHO Guidelines for Drinking-water Quality. RainbowHome is a neutral aggregator — no purifier brand pays for placement here. Exact BIS acceptable/permissible figures and WHO palatability boundaries should be confirmed against the current published standards before relying on a specific number.