"The ideal solution of depleting ground water resources in India is water harvesting system." How can it…

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"The ideal solution of depleting ground water resources in India is water harvesting system." How can it be made effective in urban areas?

Ghissu Editorial · Accepted Answer

Water harvesting is the cheapest way to recharge India's depleting aquifers, but in cities it works only with enforced mandates, clean recharge design, sponge-city planning, revived water bodies and demand control. The CGWB's 2025 assessment rates 730 of 6,762 groundwater units as over-exploited.

**Introduction**

The CGWB's 2025 assessment rates 730 of 6,762 units over-exploited, with extraction at 60.63% of the extractable resource. Water harvesting is the cheapest recharge tool, but in sealed cities it works only when designed, enforced and maintained.

**Why Urban Water Harvesting Underperforms**

1. **Sealed catchments**: Paving turns rain into runoff, which is why Chennai faced "Day Zero" in 2019 yet floods every monsoon.
2. **Paper compliance**: Pits are built to win a building permit and never desilted, and unfiltered recharge wells can carry sewage into aquifers.

**Making It Effective in Urban Areas**

1. **Mandate with verification**: Tamil Nadu's 2003 mandate for all buildings, backed by inspections, helped Chennai's water tables recover; Bengaluru's water board fines defaulters.

FIGURE: geography-p25-1 | Rooftop rainwater harvesting: rooftop collection, brick filter and service well

2. **Clean recharge design**: A first-flush diverter and sand filter before every recharge well protect the aquifer.
3. **Sponge city planning**: Permeable pavements and recharge zones in master plans, on the lines of China's Sponge City programme (2015), let cities absorb rain where it falls.
4. **Revive the commons**: AMRUT 2.0 and the "Catch the Rain" campaign (2021) restore lakes, tanks and stepwells such as Hyderabad's Bansilalpet stepwell.

**Way Forward**

1. **Aquifer-led siting**: NAQUIM maps should decide where recharge structures go.
2. **Demand control**: Tiered tariffs, leak control and treated sewage reuse must accompany harvesting.

**Conclusion**

Harvesting is necessary but not sufficient on its own. CGWB data show recharge from tanks, ponds and conservation structures rising from 13.98 BCM in 2017 to 25.34 BCM in 2024, a national gain that cities can share only if their structures are built and maintained.

"The ideal solution of depleting ground water resources in India is water harvesting system." How can it be made effective in urban areas?

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