IS 10500:2012 is the Indian Standard (BIS) for drinking water specification (second revision). This standard specifies the essential quality requirements for drinking water in India. It defines two levels of limits for various physical, chemical, bacteriological, and radiological parameters: an 'Acceptable Limit' and a 'Permissible Limit' for use only when no alternative water source is available.
Specifies the acceptable limits for various physical, chemical, and microbiological parameters of drinking water quality.
Acceptable / permissible limits and the mandatory bacteriological criterion.
| Reference | Value | Clause |
|---|---|---|
| pH | 6.5 – 8.5 (no relaxation) | Table 2 |
| Turbidity (acceptable / permissible) | 1 / 5 NTU | Table 2 |
| Total dissolved solids | 500 / 2000 mg/l | Table 2 |
| Total hardness (as CaCO₃) | 200 / 600 mg/l | Table 2 |
| Chloride | 250 / 1000 mg/l | Table 2 |
| Fluoride | 1.0 / 1.5 mg/l | Table 2 |
| Nitrate | 45 mg/l (no relaxation) | Table 2 |
| Iron | 0.3 mg/l (no relaxation) | Table 2 |
| Arsenic | 0.01 / 0.05 mg/l | Table 2 |
| Total coliform / E. coli | Not detectable in 100 ml (mandatory) | Table 4 |
| Residual free chlorine (when chlorinated) | ≥ 0.2 mg/l at consumer end | Cl. 4 |
IS 10500:2012 is the benchmark for potable (drinking) water quality in India — it is what you check the output of a water treatment plant, a borewell, a building's domestic supply or a packaged-water plant against. Any project with a drinking-water deliverable (water-supply schemes under JJM/AMRUT, township internal supply, STP/WTP commissioning, plumbing handover) is acceptance-tested to IS 10500.
It does not stand alone:
IS 10500 gives every parameter two numbers: the *acceptable limit* and the *permissible limit in the absence of an alternate source*. Water should meet the acceptable limit; the permissible limit may be tolerated only when no better source exists — never as a design target.
Key limits (acceptable / permissible):
Residual free chlorine of at least 0.2 mg/l is required at the consumer end when chlorination is used.
Report (treated borewell supply): pH 7.4, turbidity 0.8 NTU, TDS 1450 mg/l, total hardness 520 mg/l, fluoride 1.3 mg/l, iron 0.25 mg/l, nitrate 30 mg/l, E. coli absent/100 ml.
Assessment against IS 10500:
Verdict: *bacteriologically safe* but *chemically marginal* — usable only as a no-alternate source; recommend RO + softening for a compliant design.
1. Treating the permissible limit as the design target. The permissible column exists only for 'no alternate source' situations. Designing a treatment plant to the permissible limit is non-compliant practice.
2. Skipping the bacteriological test. Chemistry can all pass and the water still be unsafe. Total coliform / E. coli absence in 100 ml is mandatory and has *no* permissible relaxation.
3. Sampling only at the source. IS 10500 quality must hold *at the consumer tap*. Contamination enters in storage tanks and distribution — sample at the delivery point, not just the WTP outlet.
4. Ignoring residual chlorine. ≥0.2 mg/l free residual chlorine at the far end is what keeps distributed water safe; many handover tests omit it.
5. Not re-testing after the monsoon. Borewell chemistry (fluoride, nitrate, TDS) shifts seasonally — a one-time pre-monsoon test is not a year-round clearance.
IS 10500:2012 is the second revision and a major one — it consolidated ~94 parameters (organoleptic, general, toxic, radioactive, pesticides, bacteriological) and removed several relaxations that the 1991 version allowed (notably iron). Amendments have since fine-tuned a few limits, so always work from the latest amended copy.
It is a BIS *mandatory* certification scheme for packaged drinking water, which is why bottled-water plants treat it as a licence condition rather than a guideline. For scheme water under Jal Jeevan Mission/AMRUT it is the contractual quality clause, but field testing is often done with FTK kits whose accuracy is limited — for compliance and disputes, insist on a NABL-accredited lab report against IS 3025/1622 methods, not a field-kit colour chart.
| Parameter | IS Value | International | Source |
|---|---|---|---|
| Arsenic (As) | 0.01 mg/L (Acceptable Limit) | 0.01 mg/L | WHO GDWQ |
| Lead (Pb) | 0.01 mg/L | 0.005 mg/L | EU Directive 2020/2184 |
| Fluoride (F) | 1.0 mg/L (Acceptable), 1.5 mg/L (Permissible) | 1.5 mg/L | WHO GDWQ |
| Nitrate (as NO₃) | 45 mg/L | 50 mg/L | WHO GDWQ |
| Turbidity | 1 NTU (Acceptable), 5 NTU (Permissible) | <1 NTU for effective disinfection; can be up to 5 NTU | WHO GDWQ |
| Total Dissolved Solids (TDS) | 500 mg/L (Acceptable), 2000 mg/L (Permissible) | No health-based value; <600 mg/L is good, >1000 mg/L is poor palatability | WHO GDWQ |
| E. coli | Must not be detectable in any 100 ml sample | Must not be detectable in any 100 ml sample | WHO, EU, US EPA |
| pH | 6.5–8.5 | 6.5–9.5 (operational range, not health-based) | EU Directive 2020/2184 |