The monsoon of 2018 has been bountiful to the reservoirs in the Cauvery basin. All of them and the Kabini reservoir are overflowing at rates never before experienced. These are extraordinary times of surplus. In Tamil Nadu the Mettur dam too is overflowing and the waters have wisely been used to fill many lakes and tanks downstream. This has resulted in aquifers filling up. Wells as deep as 80 feet have been reported to have filled up after 10 years near the small town of Musiri on the banks of the Cauvery.
It is in times of plenty that water must be stocked up for times of shortage. Every building, especially those not connected to the city utilities, can become their own water suppliers and waste-water managers. Here is a small checklist on how to go about it.
Store rainwater: Rainwater must be stored at various levels of the house. A clean catchment such as a staircase roof provides an opportunity to store what can be called lifeline water. Water that, after simple treatment, can be used for drinking and cooking. Overflows from this tank can then be collected in an underground sump designed for the purpose. Excess water from the sump can be led into a recharge well, to fill up aquifers. The well can be as small as 2 feet in diameter and 10 feet deep, depending on the soil character.
Design for water-efficient fixtures: Demand management is an extraordinarily powerful weapon. The less water we use, the more efficiently we use it, the more water there will appear to be as available to us. Taps, showers, WCs, and garden systems such as drip irrigation save water and must be used.
Reuse used water: Simple systems can pick kitchen water without oil and grease and soak it in the garden through French drains for trees and plants to pick up with their roots.
Recycle water: With simple treatment, bathroom water and clothes wash can be recycled for toilet flushing and for cleaning floors.
Allow soil water percolation: Do not pave all around the house. Leave some space for rainwater to moisten soil.
Use solar water heaters: Much of the water used in river ecosystems is to generate energy, in thermal power plants or hydro-electric plants. By using solar energy for say water heating, much water can be saved in the river basins we occupy.
Compost kitchen waste: Not only will it stop pollution of waters but composted kitchen waste will enhance soil water retention capacity and improve soil capacity to nourish plants.
Simple steps in every building and every apartment will build resilience in an era of climate change where swings in rainfall pattern and temperature has become the norm. Smart building design offers the opportunity to create water banks and groundwater banks wherever we build. This would be water wisdom.