Water Harvesting - Ancient Tanks

As humanity grapples with the escalating challenges of water scarcity, exacerbated by climate change and burgeoning populations, the quest for sustainable water solutions leads us to an often-overlooked yet profound repository of wisdom: the ancient water harvesting systems meticulously developed by our ancestors. Across the Indian subcontinent, for millennia, a sophisticated network of traditional tanks – known by diverse names such as Taḍāga (तडाग) in Sanskrit, Eri (ஏரி) in Tamil Nadu, Kere (ಕೆರೆ) in Karnataka, Cheruvu (చెరువు) in Andhra Pradesh and Telangana, or temple tanks called Pushkariṇī (पुष्करिणी) – formed the lifeblood of communities, ensuring water security, ecological balance, and social harmony.

These are not mere holes in the ground but marvels of indigenous engineering, community effort, and a deep-seated reverence for Jala (जल), or water, as a sacred, life-sustaining element. Unveiling the principles behind these ancient tanks reveals not just historical ingenuity but also timeless blueprints for a water-wise future.

Echoes of Ingenuity: Understanding Ancient Water Harvesting Tanks

Traditional water harvesting tanks in India represent a decentralized, community-scaled approach to capturing and storing precious rainwater. Their designs, adapted to diverse geographical and climatic conditions, showcase a profound understanding of local hydrology and ecological principles:

• Vast Network: From the arid plains of Rajasthan with its johads and baolis (stepwells, which are related but distinct subsurface structures) to the monsoon-rich regions of South India dotted with thousands of interconnected eris and keres, these systems were once ubiquitous. Archaeological evidence from Indus Valley sites like Dholavira reveals sophisticated water reservoirs dating back over 4,500 years.

  
  

• Diverse Terminology, Common Purpose: While names varied regionally, the core purpose was consistent: to collect seasonal rainwater and surface runoff, store it for extended periods, and utilize it for irrigation, domestic needs, livestock, and crucially, for recharging groundwater.

  
  

• Sacred and Secular: Many tanks were directly associated with temples (pushkariṇīs or kalyāṇīs), imbued with sacredness and used for ritual purification. Others were primarily for agricultural and community use, yet still often managed with a sense of collective responsibility and respect.

Blueprints of Sustainability: Design and Function of Traditional Tanks

The design of these ancient tanks, though varying in scale and specific features, often followed remarkably astute principles:

1. Strategic Location and Catchment: Tanks were typically sited to maximize the natural collection of rainwater from their catchment areas, utilizing gravity and natural slopes. Series of tanks were often interconnected, with overflow from one feeding the next, creating a cascade system that optimized water retention and minimized wastage.

   
   

2. Embankments and Bunds: Earthen or stone embankments (bunds) were constructed, often with impressive engineering skill, to impound water across natural depressions or valleys. The scale of some of these bunds, like those of the Chola-era eris, is monumental.

   
   

3. Inlets, Outlets, and Sluices: Carefully designed inlets allowed rainwater and runoff to enter the tank. Sluices (thoomu in Telugu, madagu in Tamil) at various levels permitted controlled release of water for irrigation, ensuring equitable distribution. Surplus weirs (alugu or marva) allowed excess water to escape safely during heavy monsoons, preventing breaches.

   
   

4. Silt Management: Many tanks incorporated features like silt traps or settling ponds at the inlet to reduce the accumulation of sediment, which would otherwise diminish storage capacity. Periodic community-led desilting was also a common practice.

   
   

5. Percolation and Groundwater Recharge: A key, often unstated but vital, function of these surface water bodies was the significant recharge of groundwater aquifers. The slow percolation of stored water replenished local wells and springs, ensuring water availability even during dry seasons.

   
   
   
   

More Than Just Reservoirs: The Multifaceted Roles of Ancient Tanks

These traditional water bodies were central to the ecological and social fabric of their communities:

• Lifeblood of Agriculture: They provided crucial irrigation for staple crops like rice, especially in regions dependent on seasonal monsoons, ensuring food security and rural livelihoods.

  
  

• Quenching Thirst: They served as sources of drinking water for humans and livestock, and for domestic uses like washing.

  
  

• Replenishing Bhūmi (Earth): Beyond surface storage, their most profound ecological contribution was groundwater recharge, maintaining the health of the local water table and sustaining wells and vegetation.

  
  

• Sanctuaries of Life: Tank ecosystems themselves became havens for local biodiversity, supporting aquatic life, attracting birds, and providing water for wild animals. The surrounding vegetation often flourished due to the increased soil moisture.

  
  

• Microclimate Regulation: Large water bodies had a moderating effect on the local microclimate, providing a cooling influence.

The Sacred Flow: Water Reverence and Temple Tanks (Pushkariṇīs)

The reverence for water as a sacred element (Āpas, आपस्, or Jala Devatā, जल देवता) in Dharmic traditions played a significant role in the preservation and meticulous maintenance of many water bodies, especially temple tanks.

• Pushkariṇīs/Kalyāṇīs: These tanks, integral to temple architecture, were (and are) used for ritual ablutions by devotees before entering the sanctum, for sacred baths of the temple deities during festivals, and for other ceremonial purposes.

  
  

• Sacred Symbolism: The water in these tanks was often considered holy, sometimes symbolically equated with sacred rivers like the Gaṅgā. The design and upkeep of temple tanks reflected this sanctity, often featuring beautiful stone steps, mandapas (pavilions), and intricate carvings. This spiritual association fostered a deep respect for water quality and the cleanliness of the tank environment.

Community as Custodian: The Social Fabric of Tank Management

A hallmark of traditional tank systems was their robust community-based management:

• Collective Effort: Tanks were often built and maintained through the collective labor and resources of the local village or community.

  
  

• Local Governance: Well-defined rules and responsibilities for water allocation, desilting, bund repair, and conflict resolution were often managed by village councils or traditional water user associations. This fostered a sense of ownership and shared responsibility.

  
  

• Social Cohesion: The tank often served as a social and cultural hub, a gathering place for the community, especially during festivals or daily chores, strengthening social bonds.

  
  

This decentralized, participatory approach to water management was highly effective and resilient.

The Ebbing Tide: Decline and Neglect of Ancient Tank Systems

Unfortunately, over the past few centuries, many of these remarkable traditional water harvesting systems fell into decline due to a confluence of factors:

• Colonial Policies: British colonial administration often prioritized large-scale, centralized irrigation projects (canals, dams) and revenue-focused land management, leading to the neglect of local, community-managed tank systems. Traditional village governance structures were also weakened.

  
  

• Shift to Groundwater Extraction: The advent of borewell technology and subsidized electricity for pumping led to an over-reliance on groundwater, reducing the perceived need for maintaining surface tanks.

  
  

• Breakdown of Community Management: Erosion of traditional community structures and a shift towards state control often led to a loss of local ownership and responsibility for tank upkeep.

  
  

• Encroachment and Siltation: Many tanks became silted up due to neglect, and their catchment areas or tank beds were encroached upon for agriculture or urban development.

Reviving the Wells of Wisdom: The Modern Relevance of Ancient Tanks

Today, there is a growing global recognition of the profound wisdom embedded in these ancient water harvesting systems. In the face of increasing water scarcity, depleting groundwater levels, and the challenges of climate change, the revival and restoration of traditional tanks offer immensely valuable solutions:

• Effective Rainwater Harvesting: Tanks are ideal for capturing and storing precious monsoon rains, which might otherwise be lost as runoff.

• Drought Mitigation and Water Security: They provide a buffer during dry periods and enhance local water security, reducing dependence on distant or unreliable sources.

• Sustainable Groundwater Recharge: Restored tanks significantly contribute to replenishing vital groundwater aquifers.

• Ecological Restoration: They can help revive local ecosystems, support biodiversity, and improve soil moisture.

• Community Empowerment: Tank restoration projects that involve local communities can strengthen local governance, create livelihoods, and foster a renewed sense of environmental stewardship.

  
  

Pioneering work by individuals like the late Anupam Mishra, who meticulously documented India's traditional water wisdom in works like "Aaj Bhi Khare Hain Talaab" (Ponds are Still Relevant), has been instrumental in inspiring this revival.

The ancient water harvesting tanks of India are far more than relics of a bygone era. They are sophisticated, sustainable, and community-centric systems that embody a deep understanding of ecological principles and a profound reverence for water as the elixir of life. Their enduring legacy offers timeless lessons and practical blueprints for building a water-secure and environmentally harmonious future. To learn from them is to drink from a deep well of ancestral wisdom.