The short answer: Hard water is water carrying a lot of dissolved calcium (Ca²⁺) and magnesium (Mg²⁺), picked up as groundwater moves through limestone and chalk. On the USGS/WHO scale it is soft under 60 mg/L CaCO₃, moderately hard 60–120, hard 120–180, very hard above 180. But India's own drinking-water standard (BIS IS 10500:2012) allows 200 mg/L as "acceptable" and 600 mg/L as "permissible", so water that is legally fine here can be very hard by the global scale. It is safe to drink, and it is genuinely hard on soap, plumbing, appliances and hair. You can check yours in two minutes with a bottle and a few drops of soap.
Check your water: measured hardness for 78 Indian cities, from 15,127 CGWB monitoring stations.
On this page
- What makes water hard
- Hard vs soft: the two scales, and the mix-up worth avoiding
- How to test your water in two minutes
- Where India's water is hardest
- Is hard water bad for you?
- What hard water does to hair
Groundwater supplies roughly 50% of India's urban water and 85% of its rural water (Central Ground Water Board, Dynamic Ground Water Resources of India, 2023), and groundwater is where hardness comes from. That single fact is why "hard water" is an everyday Indian problem rather than a technical curiosity.
What makes water hard
Rain falls soft. Hardness is picked up on the way to your tap: as water moves through limestone, chalk and dolomite, it dissolves calcium and magnesium out of the rock. Deep borewell water has had the most contact with rock, so it is usually the hardest; surface water from lakes and rivers is usually the softest.
Two other things follow from those ions, and they are the reason hardness is noticeable at all:
- Soap stops working properly. Calcium and magnesium react with the fatty acids in soap to form an insoluble scum: the grey ring in the bucket, the film on tiles, the shampoo that will not lather however much you use.
- Scale forms when water is heated. Heat drives dissolved calcium bicarbonate out of solution as solid calcium carbonate. That is the white crust in your kettle, the crust on the geyser element, the slow death of a washing machine.
Hard vs soft: the two scales, and the mix-up worth avoiding
Hardness proper is measured in a lab as mg/L of calcium carbonate (CaCO₃):
| Classification | mg/L as CaCO₃ |
|---|---|
| Soft | under 60 |
| Moderately hard | 60–120 |
| Hard | 120–180 |
| Very hard | above 180 |
What you can actually measure at home is TDS (total dissolved solids), in ppm, which is what a ₹300 meter reads. The working bands we use for hair: under 150 ppm soft, 150–300 moderate, 300–500 hard, 500–1000 very hard, over 1000 extremely hard.
Here is the mix-up almost every article makes, including some of ours in earlier drafts: TDS is not hardness. TDS counts everything dissolved, including sodium, chloride, sulphates and nitrates, not just calcium and magnesium. Water can read high TDS and be relatively soft, or moderate TDS and be quite hard. TDS is a useful, cheap proxy; hardness is the actual measurement. If a number matters to you, get a hardness test, not just a meter reading.
How to test your water in two minutes
- The soap test. Fill a clear bottle one-third with tap water, add a few drops of plain liquid soap (not detergent), cap it and shake hard. Soft water gives you a thick head of lather and clear water underneath. Hard water gives you thin, quickly-collapsing bubbles and cloudy, milky water.
- Look around the house. White scale on taps, kettle and geyser; spots on glassware; stiff laundry; soap scum on tiles. Those are hardness telling on itself.
- A TDS meter gives you a ballpark in seconds. Just read it as "how mineral-loaded is this," not as a hardness figure.
- The real number: your municipal supplier's water-quality report, or a lab test for total hardness as CaCO₃. If you are on a borewell or tanker, a lab test is the only honest answer, because those vary by depth, season and supplier.
Where India's water is hardest
Reported ranges compiled from public groundwater and water-quality data, not deSal lab measurements, put it roughly like this:
- Softest: Mumbai, on lake-fed municipal supply, a reported 80–150 ppm TDS. Much of Kolkata and Chandigarh sit gently in the middle.
- Split by supply: Bangalore is two cities in one. Cauvery municipal water runs soft-to-moderate at a reported 120–200 ppm; borewell and tanker supply in the outer corridors (Whitefield, Sarjapur, Bellandur, HSR, Electronic City) runs far harder, up to around 1,000 ppm. A peer-reviewed study of Bangalore's West Zone measured 124–272 mg/L CaCO₃ (mean 142.4), "hard" on the lab scale.
- Hardest: borewell belts in Chennai (OMR, Velachery, Tambaram), Gurgaon and Jaipur routinely cross 1,000 ppm. Delhi's South/Yamuna supply is reported at 400–600 ppm.
The practical takeaway: hardness is a pincode-and-supply question, not a city question. Your neighbour on Cauvery water and you on a borewell can have completely different water.
Is hard water bad for you?
Short version: it is not a drinking-water safety problem, and the honest evidence on health effects is thinner than most blogs pretend.
- Drinking it. The WHO sets no health-based guideline value for hardness. It is handled as an acceptability issue (taste, scale), not a toxicity one. Calcium and magnesium in water are dietary minerals.
- Skin. This is where the most interesting evidence sits, and it cuts both ways. Living in a hard-water area was associated with up to an 87% higher risk of eczema at three months of age in a UK birth-cohort study (King's College London, 2016), and reviews find higher eczema prevalence in hard-water areas generally. But when researchers ran the actual experiment, the Softened Water Eczema Trial, 336 children randomised to an ion-exchange softener or usual care, the softener delivered no additional clinical benefit (Thomas et al., PLOS Medicine, 2011). Association is real; the fix did not follow. Anyone selling you certainty here is overselling.
- Hair. This is the effect people notice fastest, and it is mechanical rather than medical: the minerals deposit on the hair's cuticle as a film. More on that below.
- Your house. Not controversial at all: scale costs you geyser efficiency, appliance life and soap.
What hard water does to hair
The minerals do not all rinse away. Some deposit onto the cuticle, the shingle-like outer layer of each strand, and build up wash after wash into a film. That film is what people are describing when they say hair feels rough, dull, "sticky then dry," heavy, or never quite clean, and it is why conditioners and masks stop seeming to work: they cannot get through it.
On strength, the research genuinely disagrees with itself, so here is both sides. One trial at high hardness (486.7 mg/L) found hard water significantly reduced hair's breaking force (254.84 → 234.16, p=0.001). Another, at a lower 212.5 ppm, found no significant difference (p=0.858). What both agree on is buildup, roughness and dryness.
Hair fall is not on that list. Hard water is linked to breakage, dryness and buildup, not to follicular shedding, and the evidence there is mixed at best. If you are shedding, that points at thyroid, iron or hormonal causes and deserves a dermatologist, not a shampoo aisle. Treat any product sold as a hard-water cure for hair loss as a claim running ahead of the science.
What actually fixes hard water: three different jobs
These get sold interchangeably, and they are not interchangeable at all:
- A water softener (ion exchange) is the only one that changes the water itself, swapping calcium and magnesium for sodium across the whole house. It stops new scale. It is also the most expensive, needs salt and maintenance, and adds sodium.
- A shower or tap filter reduces some of what reaches you at that one outlet. Useful, cheaper and point-of-use, but it does nothing about what is already deposited on your hair, and it does not travel with you.
- A chelating shampoo does the opposite job: it removes the minerals already sitting on the hair. A chelator like Disodium EDTA wraps around calcium, magnesium, copper and iron ions from multiple points at once and holds them in a soluble complex that leaves with the rinse instead of redepositing.
Filter or softener = less mineral arriving. Chelating shampoo = mineral removed from the hair. If your water is severe, the two together make sense; if you only do one, do the one that matches the problem you can actually feel.
For the definition, how water becomes hard and where India’s BIS and WHO limits sit, see what hard water is, and India’s limits. This page is about measuring your own tap.
Where deSal fits
deSal Hard Water Defense is a chelating shampoo built on that spec: Disodium EDTA for the mineral removal, pH 5.45 (inside hair's healthy 4.5–5.5 window, so the cuticle stays flat rather than lifting the way an alkaline wash makes it), plus D-Panthenol, Hyaluronic Acid and Argan Oil for the dryness hard water leaves behind. It is ₹764 for 220 ml (roughly ₹4/ml), made in India, SLS- and paraben-free, vegan and cruelty-free, and in-vivo tested at Mascot Spincontrol: clinically tested, dermatologically tested and non-irritant, under an Ethics Committee-approved protocol on healthy volunteers per IS 4011:2018, dated 14 July 2026.
Two honest limits: that in-vivo result is a safety finding, not an efficacy measurement, and years of accumulated buildup take several washes to work through rather than one. And if your water reads under roughly 150 ppm, you do not need a chelating shampoo at all — we would rather say so than sell you a bottle you do not need.
FAQ
What is hard water? Water with a high level of dissolved calcium and magnesium, picked up as it passes through limestone and chalk. Above 180 mg/L CaCO3 it is classed as very hard on the USGS/WHO scale; India's BIS standard allows 200 mg/L as acceptable and 600 mg/L as permissible.
Is hard water safe to drink? Yes. The WHO sets no health-based guideline value for hardness, it is treated as an acceptability issue rather than a safety one. The calcium and magnesium in it are dietary minerals.
How do I know if my water is hard? Shake a third-full bottle of tap water with a few drops of plain liquid soap: thin bubbles and cloudy water mean hard. Scale on the kettle and taps, poor lather and soap scum say the same thing. For a real number, get a total-hardness test rather than relying on a TDS meter.
Is TDS the same as water hardness? No. TDS counts every dissolved solid, including sodium, chloride and sulphates; hardness counts only calcium and magnesium, as calcium carbonate. TDS is a cheap proxy, not the measurement.
Is Bangalore's water hard? It depends on your supply. Cauvery municipal water is reported at a soft-to-moderate 120-200 ppm; borewell and tanker water in corridors like Whitefield and Sarjapur runs up to around 1,000 ppm. A peer-reviewed West Zone study measured 124-272 mg/L CaCO3.
Does hard water cause hair fall? No. Hard water is linked to mineral buildup, dryness, roughness and breakage, and studies even disagree on strength loss. Shedding has other causes, see a dermatologist rather than switching shampoo.
Will a water filter fix hard-water hair? No, though it does something useful. Hardness and TDS read about the same before and after the cartridge, which is what the filter makers own specifications say. The chlorine benefit is real and worth having. For the mineral load sitting on your hair, a chelating wash is the tool that removes it.
What does it mean when a filter says it neutralises hardness? It means the minerals are still in the water. Scale conditioning was developed to stop pipes and heaters furring up, and where it is tested it is tested against scale on plumbing. A hair shaft is a charged protein surface rather than a pipe, and no published test covers it.
How often can you actually use a chelating shampoo? In a hard-water home it can be the regular wash. On soft or moderate water the deposit returns slowly, so about once a week is enough. Where the water is soft, weekly does the job.
Sources
- Water hardness classification: usgs.gov/special-topics/water-science-school/science/hardness-water; WHO, Hardness in Drinking-water background document (no health-based guideline value)
- India's drinking-water limits (total hardness 200 mg/L acceptable, 600 mg/L permissible): BIS IS 10500:2012
- Groundwater share of India's water supply (~50% urban, ~85% rural): Central Ground Water Board, Dynamic Ground Water Resources of India 2023, cgwb.gov.in
- Hard water associated with higher eczema risk in infants: King's College London / Perkin et al., 2016
- Randomised trial finding water softeners gave no additional clinical benefit for childhood eczema: Thomas et al., PLOS Medicine 2011 (Softened Water Eczema Trial), journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.1000395
- Hard water reduced hair's breaking force at high hardness: pmc.ncbi.nlm.nih.gov/articles/PMC6028999/
- No significant strength change at 212.5 ppm: pmc.ncbi.nlm.nih.gov/articles/PMC3927171/
- Shampoo pH, cuticle friction and breakage: Gavazzoni Dias et al., Int J Trichology 2014, pmc.ncbi.nlm.nih.gov/articles/PMC4158629/
- EDTA chelation binds metal ions into a rinse-away complex: scienceinsights.org/what-is-edta-a-chelating-agent-with-many-uses/
