- 2071 Shrawan · 4 marks
Why groundwater; quality parameters
Short answer
Ground water is chosen because it is naturally filtered, clear, pathogen-free, constant in quality and temperature, dependable, and needs little treatment. Common parameters are hardness, iron/manganese, arsenic, fluoride, nitrate, chloride/TDS, pH/CO2/H2S, and bacteria; each affects health and requires specific treatment such as softening, aeration, adsorption, or chlorination.
Why is a ground water source generally chosen for supplying a drinking water scheme? What are the common ground water quality parameters? Discuss them with reference to health and treatment.
Why ground water is chosen
- It is naturally filtered during passage through the soil, so it is clear and generally free from pathogens.
- Quality and temperature stay almost constant through the year.
- Yield is dependable even in the dry season, and wells can be built near the consumers, saving transmission cost.
- Little or no treatment is needed (often only chlorination), which makes it economical.
- It is less exposed to surface pollution and is easy to develop in phases.
Common ground water quality parameters
| Parameter | Concern for health | Treatment |
|---|---|---|
| Hardness (Ca, Mg) | Scaling, soap waste; not harmful | Lime-soda or ion exchange softening |
| Iron and manganese | Taste, staining, pipe encrustation | Aeration, sedimentation, filtration |
| Arsenic (Terai) | Toxic, causes skin lesions and cancer (limit 0.05 mg/l) | Adsorption, coagulation, special filters |
| Fluoride | Dental/skeletal fluorosis above 1.5 mg/l | Activated alumina, Nalgonda technique |
| Nitrate | Methaemoglobinaemia (blue baby) above 50 mg/l | Ion exchange, dilution |
| Chloride, TDS | Salty taste, laxative effects | Desalination or alternative source |
| pH, dissolved CO2, H2S | Corrosion, odour | Aeration, pH adjustment |
| Bacteria (coliforms) | Disease, in shallow wells | Chlorination |
Regular testing, especially for arsenic in Terai tube wells, is necessary before use.
✓ Answer checked by Claude Opus 5.5 (high effort)
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