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October 16, 2026If you rely on a borewell for drinking water, whether for a home, school, housing society, hospital or factory canteen, one document quietly defines what “safe” means in India: IS 10500, the Bureau of Indian Standards specification for drinking water. Understanding its key parameters helps you read test reports, choose treatment equipment and keep your water safe.
What Is IS 10500?
IS 10500 sets limits for physical, chemical, microbiological and other parameters in drinking water. It is widely used as the benchmark by authorities, laboratories and treatment designers. The current widely referenced edition is IS 10500:2012, with subsequent amendments.
Acceptable vs Permissible Limits
For many parameters, the standard gives two values:
- Acceptable limit: the value at which water is considered suitable
- Permissible limit in the absence of an alternate source: a relaxed value that may be tolerated only when no better source is available
The permissible limit is not a target. If your water exceeds the acceptable limit, treatment is generally advisable.
Key Physical Parameters
Turbidity
Cloudiness from suspended particles. Turbid water can shield microorganisms from disinfection.
Colour, Odour and Taste
Water should be agreeable. Unusual colour, smell or taste often signal contamination.
pH
The standard specifies a range of 6.5 to 8.5.
Key Chemical Parameters
Total Dissolved Solids
Acceptable limit of 500 mg/l, with a permissible limit of 2,000 mg/l in the absence of an alternate source. High TDS affects taste and can indicate high salinity.
Total Hardness
Acceptable limit of 200 mg/l as CaCO3, with a permissible limit of 600 mg/l. Hard water causes scaling and affects soap use.
Fluoride
Acceptable limit of 1.0 mg/l, with a permissible limit of 1.5 mg/l. Excess causes dental and skeletal fluorosis.
Nitrate
Limit of 45 mg/l. High levels are especially dangerous for infants.
Iron
Excess iron causes reddish-brown water, staining and metallic taste. The standard specifies a limit, which has been revised through amendments, so check the current value with your laboratory.
Arsenic
Limit of 0.01 mg/l. Long-term exposure is a serious health risk.
Chloride and Sulphate
High levels affect taste and can contribute to corrosion.
Microbiological Parameters
Drinking water must be free from E. coli and coliform bacteria in samples tested as per the standard. Microbiological contamination is the most immediate health risk and can occur even when chemical parameters look fine. Borewells near septic tanks or drains are particularly vulnerable.
What Borewell Users Should Test
At a minimum, a borewell water test should include:
- pH, turbidity and TDS
- Total hardness, calcium and magnesium
- Iron and manganese
- Fluoride and nitrate
- Chloride and sulphate
- Microbiological tests for coliforms and E. coli
In regions known for arsenic or other specific contaminants, include those as well.
How Often to Test
- A full analysis when the borewell is first used and before designing treatment
- Periodic retesting, especially before and after monsoon
- Microbiological testing more frequently for institutions and food businesses
- After any change in taste, colour or odour
Matching Treatment to Results
- High turbidity: sand or multi-media filtration
- High iron: iron removal filters
- High hardness: softening or RO
- High TDS, fluoride or nitrate: RO or specific removal technologies
- Microbial contamination: disinfection such as UV or chlorination, plus fixing the source of contamination
Conclusion
IS 10500 provides a clear framework for safe drinking water. For borewell users, regular testing against its parameters, combined with the right treatment and good wellhead protection, ensures water that is genuinely safe for daily consumption.
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