Water Harvesting Technologies

 A World Bank study puts the plight of the country in perspective:

• 163 million Indians lack access to safe drinking water;
• 210 million Indians lack access to improved sanitation;
• 21% of communicable diseases are linked to unsafe water.

Technologies to harness fresh water:

1. Rainwater Harvesting: It is a process involving collection and storage of rain water (with the help of artificially designed system) that runs off natural or man-made catchment areas. For example, roof top, compounds, rock surface or hill slopes or artificially repaired impervious/semi-pervious land surface.
   • Pros
     1. It reduces Runoff loss.
     2. Helps meet rising demand of water by recharging the water table.
     3. No land is wasted for storage purpose.
     4. No population displacement is involved.
     5. Increases the productivity of aquifer and reduces urban flooding.
   • Cons: 
     1. High installation charges.
     2. Lack of awareness and education.
2. Desalination: Converts salt water into freshwater using reverse osmosis (RO).
   • Pros: 
     1. Abundance of Seawater around India.
     2. RO is commercially proven and the dominant technology.
     3. It is easier for attracting the private players.
   • Cons: 
     1. Hyper Salinity : Deposition of brine (highly concentrated salt water) along the shores. This reduces the availability of prawn, sardine and mackerel.
     2. The construction of the RO plants required troves of groundwater.
     3. Desalinated water can also be acidic to both pipes and digestive systems.
3. Low Temperature Thermal Desalination (LTTD) : uses the availability of a temperature gradient between two water bodies or flows to evaporate the warmer water at low pressure and condense the resultant vapour with the colder water to obtain freshwater.
   • Pros: 
     1. Enables to control the quality of product water in order to provide either good quality drinking water or boiler grade water as the situation warrants.
   • Cons:
     1. Draws power from diesel sets.
     2. (refer the above image)

However, the water crisis of India cannot be solved by just one type of solution. Thus, technology alone cannot be a panacea. There is a need for multi-pronged solution to tackle the crisis of water.

Other measures needed:

1. India’s priority must be:
   • To make our irrigation and water systems amenable to modern concepts.
   • To complete irrigation and water sector reforms.
   • To implement improved water management, governance and regulation practices.
   • Pricing system for water: For making people use water efficiently
2. Deepen our understanding of our water resources and usage and put in place interventions that make our water use efficient and sustainable.
3. Augmentation of watersheds that can store more good water, for use in agriculture and to serve habitations.
4. Strict pollution control enforcement.
5. Decentralisation of irrigation commands, offering higher financial flows to well-performing States through a National Irrigation Management Fund.
6. Groundwater extraction patterns need to be better understood through robust data collection.
7. Pollution can be curbed by levying suitable costs.
8. A legal mandate will work better than just competition and cooperation; it would make governments accountable.
9. Urban India needs to focus on recycling and harvesting water, having better testing and purification facilities and increase public awareness on the need to conserve water.
10. Large catchment areas need to be developed around water bodies so that natural recharge of groundwater takes place. A good example is the Seog catchment area which has been denoted as a wildlife sanctuary and where no construction is allowed.
11. Grey water recycling, a method of recycling wastewater from kitchen sinks, showers and laundry fixtures. Grey water recycling helps reduce household water usage by about 50% .
12. This year’s World Water Development Report makes it clear the importance of nature-based solutions.

Conclusion:

The water governance ought to be made transparent, accountable and participatory in every sub-sector, including management of rivers, groundwater, floods, and biodiversity, among others.