Understanding Water Quality Standards in South India
The Bureau of Indian Standards (BIS) has set forth guidelines (IS 10500:2012) to ensure the safety and palatability of drinking water. These standards specify acceptable and permissible limits for various physical, chemical, and biological parameters.
Table 1: Key Drinking Water Quality Parameters as per BIS Standards
| Parameter | Acceptable Limit | Permissible Limit (In Absence of Alternate Source) |
|---|---|---|
| pH | 6.5 – 8.5 | No relaxation |
| Total Dissolved Solids (mg/L) | 500 | 2000 |
| Total Hardness (as CaCO₃) (mg/L) | 200 | 600 |
| Chloride (mg/L) | 250 | 1000 |
| Nitrate (mg/L) | 45 | No relaxation |
| Fluoride (mg/L) | 1.0 | 1.5 |
| Iron (mg/L) | 0.3 | No relaxation |
| Turbidity (NTU) | 1 | 5 |
*Source: Tamil Nadu Water Supply and Drainage Board (TWAD) *
Chennai & Nearby Areas (Tiruvallur, Sriperumbudur, Chengalpattu, Kanchipuram, Pondicherry)
Chennai Groundwater: Studies have shown that parameters like pH, fluoride, iron, and calcium are within permissible limits in most areas. However, high TDS (Total Dissolved Solids) and hardness are common in localities like Pallavaram, Tambaram, and Velachery due to over-extraction and seawater intrusion. Continuous water quality monitoring and household RO treatment are recommended, especially in coastal and peri-urban belts.
Bangalore & Nearby Areas (Tumkur, Hosur, Nelamangala, Ramanagara, Mysuru)
Bangalore Groundwater: The city’s outskirts suffer from nitrate contamination, often exceeding 50 mg/L, due to unregulated sewage and agricultural runoff. Hardness and TDS levels are also high in Borewell sources across Whitefield, Electronic City, and Yelahanka. Reports from the Central Ground Water Board (CGWB) highlight contamination hotspots in Hosur and Tumkur, calling for urgent need of domestic and industrial water treatment systems.
Hyderabad & Nearby Areas (Medchal, Rangareddy, Sangareddy, Nalgonda, Warangal)
Hyderabad Groundwater: Fluoride contamination is a major concern in areas like Nalgonda and Rangareddy, where levels have been reported above 1.5 mg/L, causing fluorosis risks. In urban Hyderabad, iron and microbial contamination are seen in many older water pipelines and shallow wells. Treatment via UV, RO, and iron removal filters is essential across various zones.
Trichy & Nearby Areas (Karur, Thanjavur, Pudukkottai, Perambalur)
Trichy Water Quality: While municipal supplies are generally treated, borewell water in outskirts like Srirangam, Lalgudi, and Thuvakudi shows high TDS and sulphates. Rural belts of Karur and Pudukkottai have reported issues with nitrate and hardness. A combination of pressure sand filtration, softeners, and UV systems is often deployed in both residential and industrial applications.
Madurai & Nearby Areas (Dindigul, Sivagangai, Theni, Ramanathapuram, Virudhunagar)
Madurai Groundwater: Reports indicate moderately high fluoride and hardness, especially in western outskirts like Melur and Thirumangalam. In Dindigul and Theni, borewells often exceed the TDS threshold of 500 mg/L. Areas near Ramanathapuram report saline intrusion. Tailored water treatment plants with RO + activated carbon are essential in these regions.
Coimbatore & Nearby Areas (Tiruppur, Erode, Pollachi, Avinashi, Mettupalayam, Ooty, Bhavani, Karur, Palakkad)
Coimbatore Water Quality: Industrial areas like Peelamedu and SIDCO estates show elevated iron, TDS, and chemical residue. In Tiruppur and Erode, textile industries contribute to color, BOD, and COD in water sources. Ooty and Mettupalayam have relatively cleaner sources, but still need basic filtration due to organic matter. Advanced treatment including multi-stage RO and iron filters is commonly installed in commercial and residential zones.
Salem & Nearby Areas (Namakkal, Dharmapuri, Krishnagiri, Tirupattur)
Salem Groundwater: Elevated levels of fluoride and nitrate are found in borewell water from regions like Attur and Mettur. In Krishnagiri and Dharmapuri, fluoride is a major public health concern, often exceeding 2 mg/L, demanding fluoride removal and remineralization units. Tirupattur faces hardness and iron challenges, typically treated using softeners and pressure sand filters.
Water Quality Needs Across South Indian Cities
Major South Indian cities like Chennai, Bangalore, Hyderabad, Trichy, Madurai, Coimbatore, and Salem face increasing challenges in maintaining clean and safe water due to rapid urbanization, groundwater depletion, and contamination. In Chennai, TDS and hardness levels are often above permissible limits, requiring RO and softener systems. Bangalore struggles with nitrate and sewage infiltration in groundwater. Hyderabad sees seasonal fluctuations and fluoride presence in outlying zones. Industrial belts in Coimbatore and Salem report high iron and turbidity levels, while Trichy and Madurai frequently need filtration for dissolved solids and microbial content. These cities require tailored water treatment plant (WTP) setups to meet residential, commercial, and industrial needs.
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