“The next chapter of sewage treatment won’t be about getting rid of water. It will be about creating a dependable source that cities and industries can draw on again.” Anuj Arora, Founder & CEO, Neuromod Aqua
For decades, the name said it all: a sewage treatment plant existed to treat sewage well enough to dispose of it.
That way of thinking is running out of road.
Indian cities keep growing, industries are using more water, and freshwater is getting scarcer and costlier to secure. The World Bank estimates that 600 million people will be living in urban India by 2036. At that scale, we can’t keep treating water as purely a hunt for new sources. Every city will also need to ask how much of its water it can use a second time.
The numbers are already striking. A 2025 study by the Council on Energy, Environment and Water (CEEW) put the opportunity in India’s treated-used-water economy at up to Rs 3.04 lakh crore by 2047. That figure combines potential market revenue with the infrastructure investment needed to scale up treatment and reuse. The same study estimated that 31,265 million cubic metres of treated used water could be available every year by then for industrial and irrigation reuse.
Policy is heading the same way. AMRUT 2.0 sets out a clear ambition: recycled treated water should meet at least 20% of a city’s total water demand and 40% of industrial water demand at the state level.
All of this changes the economics of treatment.
When treated sewage is simply discharged once it meets a standard, the STP is a cost of compliance. But when that same water can reliably stand in for freshwater used in flushing, landscaping, cooling, construction, irrigation or certain industrial processes, the plant starts producing something of value.
Nagpur shows what this can look like at city scale. CEEW has highlighted an arrangement between the public and private sectors in which 110 MLD of treated municipal water goes to the Koradi thermal power plant for a fixed annual fee. The result is a long-term industrial buyer for the water and less pressure on freshwater supplies.
But this isn’t a story only for big cities and power stations.
A hotel that reuses treated sewage for flushing and landscaping needs less freshwater. So does a commercial complex. Industries in water-stressed regions can look at whether tertiary-treated wastewater could replace freshwater in utilities or other applications that don’t touch the product. Housing projects can build reuse into the design from day one instead of bolting it on later.
The real engineering test is reliability. A second water supply is only useful if people trust its quality and know it will be there when they need it. That means designing treatment systems around how the water will be used, not just around the minimum standard for discharge. It also means monitoring, maintenance and operating discipline matter far more than they used to.
This points to a shift in the questions the sector asks. The more useful question is no longer “What outlet parameters will the STP meet?” It is “What do you plan to do with the water once it’s treated?” The answer changes the plant that needs to be built.
Pollution control will continue to drive India’s wastewater sector. But economics may soon be just as powerful a force. Once treated water has a buyer, a purpose and a price, there is a much stronger reason to keep treatment infrastructure running well.
It’s time to stop designing wastewater systems around disposal. In a water-constrained economy, yesterday’s wastewater may well be tomorrow’s most local source of supply.
The author is Anuj Arora, Founder & CEO, Neuromod Aqua
