Drinking Water Testing

Drinking Water Testing

Clean drinking water is the foundation of good health. Unfortunately, water can carry invisible threats like harmful bacteria, toxic chemicals, heavy metals, and excess minerals. To safeguard public health, drinking water testing and analysis is carried out as per Bureau of Indian Standards (BIS IS 10500:2012, revised 2021) and World Health Organization (WHO) guidelines.

What is Water Quality Testing?

Water quality testing is the scientific process of evaluating water samples to determine their physical, chemical, and microbiological composition.

• Physical testing checks turbidity, odour, taste, and colour.
• Chemical testing identifies minerals (calcium, magnesium), salts (chlorides, nitrates), and toxic contaminants (arsenic, fluoride, lead).
• Biological testing detects disease-causing organisms like E. coli and coliform bacteria.

Results are compared against prescribed standards to classify water as potable (safe for drinking) or contaminated.

Need of Drinking Water Quality Testing and Analysis

The necessity of water testing arises from multiple aspects:

1. Health and Safety
• Waterborne diseases such as cholera, typhoid, hepatitis A, and dysentery spread through contaminated water.
• In 2019, WHO estimates nearly 485,000 deaths annually worldwide due to unsafe drinking water.
2. Compliance with Standards

• In India, drinking water must meet BIS IS 10500:2012 requirements.
• Parameters like arsenic (≤0.01 mg/L), fluoride (≤1.0 mg/L), and lead (≤0.01 mg/L) are strictly monitored.

       3. Source Protection

• Rivers, lakes, reservoirs, and groundwater sources are prone to industrial effluents, agricultural runoff (pesticides, nitrates), and sewage. Testing helps identify and control pollution sources.

       4. Sustainable Development

• Regular monitoring aligns with Sustainable Development Goal (SDG) 6: Clean Water and Sanitation.

Location of Drinking Water Sampling Points

Representative sampling is the backbone of accurate testing. Points are chosen to reflect water quality at different stages:

• Source Water: Borewells, tube wells, rivers, reservoirs, lakes.
• Post-Treatment Points: At treatment plant outlets after filtration and disinfection.
• Distribution System: At different distances from supply points (tanks, pipelines, community taps).
• Consumer End Points: Schools, hospitals, hotels, offices, and households where people directly consume water.

Sampling Frequency

The frequency of drinking water sampling is defined by BIS and CPCB guidelines:

• Treatment Plant Outlet: Daily testing for residual chlorine and turbidity.
• Distribution Network: Monthly testing for bacteriological and chemical quality.
• High-Risk Areas: Weekly or biweekly sampling (schools, hospitals).
• Comprehensive Testing: Annually for all 34 physio-chemical and 3 microbiological parameters as per IS 10500.

Storage of Samples

Proper storage and handling prevent contamination or changes in water chemistry:

• For Bacteriological Testing: Sterile glass or plastic bottles with sodium thiosulfate (to neutralize chlorine). Must be tested within 6 hours.
• For Chemical Testing: Plastic or glass bottles, rinsed with the sample water (except in cases of heavy metal testing where nitric acid preservation is required).
• Temperature: Store at 2–8°C in an icebox until analysis.
• Labelling: Include date, time, location, and sampler’s name.

Drinking Water Quality Testing and Analysis

Drinking water testing includes:

1. Field Tests
• Residual chlorine using DPD kits.
• pH using portable meters.
• Turbidity with turbidity meters.
2. Laboratory Analysis
• Physio-chemical tests: TDS, hardness, chloride, nitrate, fluoride.
• Heavy metal analysis: Arsenic, lead, mercury, cadmium (using AAS/ICP-MS).
• Microbiological analysis: Detection of E. coli, total coliform, faecal streptococci using MPN (Most Probable Number) or membrane filtration methods.

3. Sampling Methods for Physio-Chemical Analysis in Laboratory

   To maintain data accuracy, standard procedures are followed:

   • Collect water from free-flowing taps (run water for 2–3 minutes before collection).
   • Do not rinse microbiological sampling bottles to avoid destroying sterilization.
   • Fill bottles leaving minimal air space.
   • Use grab sampling (single-time collection) or composite sampling (mixture of samples at intervals) depending on study requirements.
   • Transport samples in insulated boxes to the lab within 24 hours.

     Water Quality Testing Parameters

     As per BIS IS 10500 (2012), the following parameters are critical:

     1. Physical Parameters
     • Colour: Should be clear (≤5 Hazen units).
     • Turbidity: ≤1 NTU (acceptable up to 5 NTU).
     • Taste & Odour: Should be agreeable.
     • Total Dissolved Solids (TDS): ≤500 mg/L (acceptable up to 2000 mg/L).                                         
     2. Chemical Parameters
     • pH: 6.5 – 8.5
     • Total Hardness: ≤200 mg/L (acceptable up to 600 mg/L).
     • Nitrate (as NO??): ≤45 mg/L
     • Fluoride: ≤1.0 mg/L (acceptable up to 1.5 mg/L).
     • Chloride: ≤250 mg/L (acceptable up to 1000 mg/L).
     • Toxic Metals:
     • Arsenic: ≤0.01 mg/L
     • Lead: ≤0.01 mg/L
     • Mercury: ≤0.001 mg/L
     • Cadmium: ≤0.003 mg/L                                                                                                    
     3. Microbiological Parameters
     • Total Coliforms: 0 MPN/100 ml
     • E. coli: 0 MPN/100 ml
     • Pathogens: Nil                                                                                                                                  
     4. Additional Parameters
     • Residual Chlorine: Minimum 0.2 mg/L after 30 minutes contact.
     • Pesticides/Herbicides: Below detection limits.
     • Detergents/Phenolic Compounds: ≤0.001 mg/L.

     Conclusion

     Safe drinking water is a right, not a privilege. Regular testing ensures compliance with BIS standards, prevents waterborne diseases, and safeguards public health. By following correct sampling practices, storage protocols, and testing methods, communities and institutions can ensure reliable water quality monitoring.

     Whether you are a household, an industry, or a public body, partnering with an accredited drinking water testing laboratory ensures that the water you consume is truly safe and healthy.

     Virat Global Lab, a division of Aseries Envirotek India Private Limited, offers comprehensive drinking water testing services across India. With reliable sample collection, quick turnaround times, and expert interpretation of results, Virat helps clients maintain water safety, health standards, and environmental compliance—ensuring that every drop of water is safe, clean, and accountable.

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