What's in my water
Chloride and salinity — why your borewell water tastes salty
Chloride is the ion responsible for the salty taste in water, entering groundwater from natural salt deposits, seawater intrusion in coastal aquifers, and sewage.
Limits and standards
BIS publishes two figures for many parameters: an acceptable limit, and a permissible limit that applies only where no alternate source of water exists. The second is a fallback for communities without a choice — not a target to design a purchase around.
| Standard | Limit | What it means |
|---|---|---|
| BIS IS 10500:2012 — acceptable limit | 250 mg/L | — |
| BIS IS 10500:2012 — permissible in absence of alternate source | 1,000 mg/L | — |
| WHO | No health-based guideline value | WHO notes taste becomes noticeable from around 200–300 mg/L depending on the associated cation. |
Where it comes from
Seawater intrusion
The dominant cause in coastal Gujarat, Tamil Nadu, Kerala, Andhra Pradesh and around Mumbai and Chennai. Extraction lowers the freshwater head and seawater moves inland to replace it.
Natural salt deposits
Evaporite formations in arid Rajasthan and Gujarat release chloride into groundwater directly.
Sewage and industrial effluent
Both raise chloride, which is why a chloride rise alongside a nitrate rise points at sewage rather than geology.
Water softener discharge
Softener regeneration brine adds chloride to whatever it drains into — a localised contributor in areas with many softeners and poor drainage.
Why it matters
- Salty water is unpleasant to drink and changes the taste of tea, dal and everything cooked in it — the practical complaint that drives most purchases.
- Chloride is aggressive towards metal. It pits stainless steel and accelerates corrosion in geysers, pumps and plumbing, shortening equipment life measurably.
- There is no health-based limit at the concentrations normally encountered, though for anyone on a sodium-restricted diet the associated sodium can matter.
- Rising chloride in a coastal borewell is a warning about the aquifer, not just about the tap. It usually means the well is on a trajectory rather than at a steady state.
Note
Can you detect it yourself?
This is the section most purifier buying decisions skip. A handheld TDS meter is the instrument almost every Indian household is shown, and for most contaminants that matter it reads exactly the same whether the contaminant is present or not.
| Question | Answer |
|---|---|
| Can you sense it? | Distinctly salty. Chloride is one of the few contaminants where taste is a genuinely reliable indicator — a salty taste means chloride, essentially always. |
| Does a TDS meter show it? | Chloride contributes strongly to conductivity, so saline water reads high on a TDS meter. This is a case where the meter is actually informative, though it still cannot separate chloride from anything else. |
| Field / home test | Chloride test strips give a usable band cheaply. Taste plus a TDS reading is usually enough to establish the picture before deciding to test formally. |
| Laboratory test to ask for | Chloride by argentometric titration or ion chromatography — APHA 4500-Cl⁻ B or 4110 B (indicative ₹150–₹500) |
When to pay for a laboratory test
- Your coastal borewell has become progressively saltier over the years. Get chloride and TDS together, and consider whether the well has a future.
- You are specifying RO for saline feed. The membrane type and pump specification depend on the actual figure, not on a taste impression.
- Chloride and nitrate have both risen. That combination points at sewage rather than seawater and has a different fix.
What removes it
Effectiveness ratings below describe the technology working correctly, within its service life, on water or air that suits it. “Depends” means there is a condition in the caveat that decides the outcome — read it before buying.
- Reverse osmosis (RO)Effective
90–98%
The only practical household technology for chloride.
Caveat: On genuinely saline feed above about 2,000 ppm TDS, standard domestic RO struggles — recovery falls, waste rises sharply, and the membrane works outside its design envelope. A brackish-water membrane and higher feed pressure are the correct specification.
- DistillationEffective
Complete, and used at scale for genuinely saline sources. Impractical domestically.
- Anion exchangePartial
Can remove chloride but is uneconomic at the concentrations where chloride is a problem — regeneration frequency makes it impractical.
What does not work
Each of these is commonly assumed — or actively marketed — to help with chloride & salinity. None of them do.
Water softener
The most common and most expensive misunderstanding on this page. A softener exchanges calcium and magnesium for sodium. On salty water it removes hardness and leaves the salt — and adds more sodium in the process, so the water can taste worse afterwards.
Activated carbon
No capacity for chloride.
UV and UF
Neither removes dissolved ions.
Boiling
Concentrates chloride in what remains.
Frequently asked questions
Why is my borewell water salty?
Will a water softener fix salty water?
Can RO handle very salty water?
Is salty water safe to drink?
Sources
Every limit and standard quoted on this page comes from one of the documents below. Where a figure is not in one of these, we have not published it.
Bureau of Indian Standards · published 2012-05-01 · checked 2026-08-01
BIS states two figures for many parameters: an 'acceptable limit' and a 'permissible limit in the absence of an alternate source'. The second is a fallback for communities with no other supply, not a target.
Guidelines for Drinking-water Quality, 4th edition incorporating the 1st addendum
World Health Organization · published 2017-04-01 · checked 2026-08-01
Ground Water Quality in Shallow Aquifers — annual and state reports
Central Ground Water Board, Ministry of Jal Shakti, Government of India · checked 2026-08-01
District-level groundwater quality reporting. Coverage and sampling year vary by state — always check the report date for your district rather than assuming a national figure applies.
This page states what published standards say and what the physics of each technology allows. It does not state what is in your supply — no page can. Where the two questions meet is a test result, and every entry in this library says which test to ask for.