Devakula-Tadaga: Temple Tanks as Community Assets
Sacred Water, Sacred Forests
India once had millions of community tanks and thousands of sacred groves, infrastructure that harvested water, preserved biodiversity, and served communities for centuries. From Tamil Nadu's 39,000 eris to Rajasthan's stepwells to the sacred kavus of Kerala, different regions developed different solutions to the same challenge: governing shared ecological resources.
The Lake That Remembered Itself
In 2019, Chennai faced a water crisis that made global headlines. Reservoirs dried. Taps ran empty. Water was shipped in by train. Yet within the city limits, there existed something remarkable: Porur Lake, a 1,000-year-old temple tank that, unlike the modern reservoirs, had never run completely dry.
What was different? Porur wasn't a 'reservoir' in the modern sense, it was an eri, a temple tank designed as an integrated ecological system. While modern engineering treats water as a resource to be stored and extracted, the eri system treated water as a relationship to be maintained.
Across India, from Tamil Nadu's 39,000 eris to Rajasthan's stepwells to Karnataka's kalyanis, communities built water infrastructure that lasted centuries. Parallel to these, sacred groves (devara kaadu in Karnataka, kavu in Kerala, law kyntang in Meghalaya) preserved forests when all around them land was cultivated.
How did they work? What did we lose when we abandoned them? And can they be revived?
The Pan-Indian Mosaic of Water Wisdom
Tamil Nadu's Eri System: Engineering and Ecology
The eri (tank) system of Tamil Nadu is the world's most sophisticated traditional water management network. At its peak, the region had over 39,000 tanks linked in cascade systems, where overflow from one tank fed the next.
But an eri wasn't just a pond. It was a complete system:
- Ayacut (command area): The specific fields irrigated by each tank
- Kodangi (bund): The embankment, often 2-3 kilometers long
- Madagu (sluice): Gates controlling water release
- Kalingula (surplus weir): Overflow channel preventing breaches
- Neerkatti (water manager): The appointed person who managed distribution
The Chola inscriptions record detailed rules: when water is released, in what sequence, to which fields. These weren't bureaucratic regulations, they were community decisions enforced through the eri kuttam (tank assembly).
Karnataka's Kalyanis: Architecture as Worship
In Karnataka, temple tanks took a different form: the kalyani or stepped tank. Unlike the vast agricultural eris, kalyanis were smaller, architecturally elaborate, and often attached to temples.