What's in my water
Lead in drinking water — a plumbing problem, not a source-water problem
Lead is a heavy metal that enters drinking water almost entirely from plumbing — pipes, solder, brass fittings and taps — rather than from the source water itself.
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 | 0.01 mg/L | No relaxation permitted. |
| WHO provisional guideline value | 0.01 mg/L | WHO designates it provisional and states there is no known level of lead exposure without some effect — the value reflects what is achievable, not a safe threshold. |
Where it comes from
Leaded solder
Used in copper plumbing joints historically. Older buildings are the risk case, and India has no national lead-service-line inventory to check against.
Brass fittings and taps
The most common contributor in Indian homes. Brass alloys legitimately contain lead for machinability, and it leaches into standing water. This is why a new tap can raise lead, not only an old one.
Submersible pump components
Brass impellers and fittings in borewell pumps contribute in the same way.
Source water
Genuine lead in raw water is uncommon in India outside specific industrial catchments. If your lead result is high, look at the plumbing first.
Why it matters
- WHO states there is no known level of lead exposure that is without effect, and identifies young children and pregnant women as the groups of greatest concern.
- The documented associations for childhood exposure include effects on neurodevelopment. This is why the limit is set at the practical achievable level rather than at an observed threshold.
- Exposure is cumulative and there are no water-related symptoms to notice. As with arsenic, testing is the only route to knowledge.
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? | None. Lead is tasteless, odourless and invisible in water. |
| Does a TDS meter show it? | Nothing at all. At the 0.01 mg/L limit, lead contributes 0.01 ppm — five hundred times below the resolution of a handheld meter reading in whole ppm. |
| Field / home test | Consumer lead test strips exist but have poor sensitivity near 0.01 mg/L, which is the concentration that decides the question. Treat a positive strip as serious and a negative as uninformative. |
| Laboratory test to ask for | Lead by ICP-MS or graphite furnace AAS — APHA 3125 B (ICP-MS) or 3113 B (GFAAS) (indicative ₹600–₹1,500) |
When to pay for a laboratory test
- You live in a building constructed before roughly 1990 and have never tested. Older solder and fittings are the highest-probability case.
- You have young children or someone is pregnant, and the plumbing history is unknown.
- You installed an RO system and drink very low-TDS water that then travels through brass fittings to a separate tap — low-mineral water is more aggressive towards those fittings.
- You have replaced taps or plumbing recently. New brass leaches most in its first months.
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
>95%
Effective for dissolved lead. Systems certified to NSF/ANSI 58 carry a verified lead reduction claim.
- Carbon block certified to NSF/ANSI 53 for leadEffective
>99% when certified and within cartridge life
A specific engineered carbon block with lead-adsorptive media — not a generic carbon cartridge.
Caveat: The certification is the whole claim. A carbon filter without an NSF/ANSI 53 lead listing has no basis for a lead reduction claim, and most sold in India do not have one.
- DistillationEffective
Complete removal. Impractical at household scale.
- Flushing the tapPartial
Not a treatment technology, but genuinely effective and free: run the tap 30 seconds to two minutes after any long standing period before drawing drinking water.
Caveat: Reduces exposure; does not eliminate it, and does nothing about the underlying fitting.
What does not work
Each of these is commonly assumed — or actively marketed — to help with lead. None of them do.
Boiling
Lead is not volatile. Boiling reduces the water volume and raises lead concentration in what remains.
UV
No effect on dissolved metals.
Sediment filters and generic carbon
Dissolved lead passes through both. Only carbon specifically engineered and certified for lead adsorption removes it.
UF
Pore size is far too large for a dissolved metal ion.
Water softener
Softening resin has some incidental affinity for lead but is not a treatment for it and cannot be relied on.
Why the sample you take decides the answer you get
Lead concentration in a tap is not a fixed property of the water. It depends entirely on how long that water has been sitting in contact with the fitting.
Water drawn first thing in the morning, after eight hours in a brass tap, can carry many times the lead of water drawn from the same tap after two minutes of running. A laboratory testing a flushed sample will very often report a clean result from a tap that delivers a poor first-draw one.
So the sampling protocol matters more than the laboratory. Ask for a first-draw sample: taken after at least six hours of no use, straight into the bottle, before anything else runs.
Tip
The one real argument against over-purification
Most claims that RO water is 'too pure' do not survive scrutiny — the nutritional argument is weak, because drinking water is a minor contributor to dietary mineral intake for most people.
The corrosion argument is different, and it is legitimate. Water with very low mineral content and low alkalinity is more aggressive towards metal, and lead uptake from brass fittings rises accordingly. That is a plumbing chemistry fact, not a marketing line.
It matters in a narrow case: RO output stored or distributed through brass or soldered fittings before it reaches the glass. Most domestic RO units dispense through a plastic tap directly, which sidesteps the issue entirely — but a system plumbed into a building's metal distribution is a different situation, and is worth thinking about.
Frequently asked questions
Does RO remove lead from water?
Can I test for lead at home?
Do brass taps put lead in my water?
Does boiling water remove lead?
Is lead common in Indian tap water?
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
NSF/ANSI 53: Drinking Water Treatment Units — Health Effects
NSF International / American National Standards Institute · checked 2026-08-01
NSF/ANSI 58: Reverse Osmosis Drinking Water Treatment Systems
NSF International / American National Standards Institute · checked 2026-08-01
The certification standard that defines verified reduction claims for RO systems. A unit 'using NSF-certified components' is not the same as a unit certified to NSF/ANSI 58.
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.