Integrated Urban Water Management: How we can achieve water security in India

Water plays a central role in our urban environment and overall quality of life. The combined impacts of rapid population growth and climate change are now posing a severe threat to the livability and resilience of our cities.

Population growth drives intensive agricultural development, urbanisation and industrial growth, producing increased demand for clean water, yet also contributing to water pollution and competition for water resources.

The mismatch between increasing water demand and declining water quality and availability is the most critical resource issue worldwide. In India, with water scarcity issues, the problem is further intensified.

Increased variability in rainfall caused by climate change will see more frequent droughts and floods, meaning our resilience to these pressures is low. Projections of rising temperatures and highly variable rainfalls for most regions suggest significant water security issues are expected.

Current water management approach:

• Water Supply: Groundwater and surface water from reservoirs, rivers and lakes is treated and distributed to meet demands.
• Wastewater treatment and disposal: Wastewater we generate is then treated in centralised treatment plants and then discharged into rivers or the sea. Treatment helps remove nutrients and pathogens; however, harmful nutrients, pharmaceuticals and other chemicals are discharged into our waterways. Water is disposed of after single-use, so a valuable resource is wasted.
• Storm-water drainage: Storm-water drains quickly take rain/storm water runoff away from our homes and streets to avoid flooding, again a valuable resource is wasted, and large amounts of pollutants such as nitrogen, phosphorous and suspended solids are discharged into our waterways leading to algal blooms.

All three systems are linear, relying on single-use and disposal focussed on meeting only one human need: provide clean water supply, remove wastewater or prevent flooding (optional table above) and fail to consider overall urban water system impacts and ecosystem health. Nor do they provide resilience against varying climate. No Rain leads to reduced supply and too much rain leads to flooding.

An alternative approach: Integrated Urban Water Management (IUWM):

Due to ongoing risks to water supply, the water industry globally has been exploring alternative and decentralised water supply options using water streams that are currently discarded as waste (stormwater and wastewater).

This approach, known as Integrated Urban Water Management (IUWM) utilises all sources of available water and supplies fit for purpose water to meet demand instead of drinking water for all uses. Mostly, alternative water supply sources such as rainwater tanks, stormwater harvesting and treated wastewater are used for non-potable uses such as toilet flushing, garden irrigation and laundry.

Desalination of seawater: used in coastal cities to provide climate independent additional water supply, but it’s energy-intensive, unavailable to inland regions, and doesn’t address the issue of waterway pollution from wastewater and runoff, generating saline brine waste that needs disposal. Stormwater Harvesting: Instead of removing rainwater, runoff from the rooftops is collected in rain tanks for household use. Stormwater from roads, parks and driveways is collected for treatment and use. This provides additional supply source, reduces flash flooding and can divert large amounts of stormwater and pollution away from waterways. It’s only available seasonally as it’s climate dependent. Wastewater Recycling: Recycled wastewater can significantly reduce freshwater demand and we have cost-effective technology readily available to fully treat our wastewater for non-potable as well as potable reuse. Potable reuse can be Direct Potable Reuse (DPR) by supplying treated wastewater directly to households or Indirect Potable Reuse (IPR) by pumping treated wastewater into the reservoir. This approach utilises treated wastewater to provide an additional water source, provide climate-independent supply and divert large amounts of wastewater and pollution from waterways. It’s also less energy intensive than seawater desalination Importantly, a combination of stormwater and wastewater recycling can provide multiple benefits and solve water security and water pollution problems. It utilises the core principles of the circular economy by increasing resource use efficiency and reducing waste.

Why aren’t we using this approach in India?

There is significant technical know-how for wastewater treatment to every standard as demonstrated in Singapore, London and several other cities, however in India we don’t have the social license to permit wastewater recycling and reuse.

Other challenges include the significant government investment required to create infrastructure to operationalise such integrated systems, and the need for a comprehensive governance framework for multiple government areas to work together.

How do we change this before it’s too late?

We can create place-based R&D, a full-scale demonstration at a chosen site supported by education on integrated water management where all sources of water can be used for fit-for-purpose supply. The demonstration site will reduce the resource need for freshwater demand and waste generation (wastewater and stormwater), provide flood protection and improve livability in the face of climate change and population growth.

Such a facility can provide a testbed to optimise the supply mix and provide greater understanding of the challenges and opportunities presented by IUWM for use in India to meet urban water demand and reduce resources and cost. Through community engagement initiatives, it can utilise all three sets of attributes that lead to higher productivity for each unit of water used: demand reduction (Reduce), water substitution (Reuse) and water regeneration (Recycle).

The author is a Associate Professor in Environmental Engineering at The University of Melbourne. 

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