By Rohit Kakkar, Deputy Adviser, Public Health and Environmental Engineering, Ministry of Housing and Urban Affairs
India’s urban water management framework has undergone a major shift, with an increasing emphasis on wastewater treatment, reuse and sludge management. The evolving policy landscape, supported by national missions and regulatory initiatives, aims to address both infrastructural gaps and the need for sustainable water utilisation. The focus is not only on expanding treatment capacity but also on ensuring that treated wastewater and by-products are productively reused across sectors.
Current infrastructural status
Wastewater treatment infrastructure in India encompasses a range of configurations, including large-scale treatment plants and decentralised units at the colony level. In addition, nature-based systems and mechanised solutions are being deployed depending on local conditions. Irrespective of the approach adopted, treatment processes generate sludge as a by-product.
At present, urban India generates around 53,000-54,000 million litres per day (mld) of wastewater, based on standard consumption and discharge assumptions. Against this, a treatment capacity of approximately 32,000 mld has been created, while actual utilisation remains slightly lower at around 23,000 mld. The disparity between installed capacity and utilisation is attributed to uneven infrastructure development.
To address these gaps, two major government programmes – the Atal Mission for Rejuvenation and Urban Transformation (AMRUT) and the Swachh Bharat Mission (SBM) – have prioritised the expansion of sewage treatment infrastructure. Over the next five to seven years, a significant portion of the existing capacity deficit is expected to be bridged through strategic interventions under these programmes. Further, about 20,000 mld of wastewater treatment infrastructure stands sanctioned under AMRUT and SBM.
Policy and regulatory framework for reuse
The reuse of treated wastewater has emerged as an integral component of sustainable urban water management, driven by policy mandates. As an early initiative, the National Urban Sanitation Policy, 2008 mandated the reuse of at least 20 per cent of treated wastewater for non-potable purposes, thereby recognising reuse as a critical element of urban sanitation planning. The policy frameworks have also aligned with other sectors over time. For instance, the Ministry of Power’s Tariff Policy, 2016 mandates that thermal power plants located within a 50 km radius of sewage treatment plants utilise treated wastewater, thereby creating assured demand and reducing reliance on freshwater sources.
These efforts have been further reinforced through regulations under AMRUT, where cities are required to reuse at least 20 per cent of treated wastewater to offset urban water demand, while also aiming to meet up to 40 per cent of industrial water requirements through reuse. These targets reflect a shift towards demand substitution, particularly for bulk consumers such as industries. Further, under AMRUT, initiatives such as Jal Hi Amrit provide financial incentives to high-performing sewage treatment plants, particularly those demonstrating higher levels of reuse and adoption of renewable energy. Collectively, these measures indicate a structured and multi-pronged approach to mainstreaming wastewater reuse.
Sector opportunities for wastewater reuse
India’s water reuse strategy is increasingly aligned with its agricultural strengths, given that the country has one of the largest areas under cultivation globally. The sector is also the largest consumer of water. Therefore, agriculture presents a viable and scalable opportunity for the utilisation of treated wastewater, particularly at moderate treatment levels achieved through cost-effective processes. In this context, the Ministry of Housing and Urban Affairs is developing practical and safely achievable norms for the reuse of treated wastewater, particularly for agriculture and other bulk users such as industry. Parallel initiatives are also focusing on the formulation of sludge reuse standards. Given that nearly 80 per cent of water demand is driven by agriculture and around 10 per cent by industry, these sectors remain the primary targets for reuse. Additional applications such as horticulture and landscaping are also being explored, while international practices continue to reinforce the viability of such models.
In the power sector, the water requirement of thermal power plants for cooling purposes exceeds the total volume of wastewater generated by urban centres. The water demand is estimated to be three to four times higher than the potential supply from treated sewage. This indicates a substantial scope for reuse, particularly in regions where treatment facilities are located within feasible conveyance distances. At the same time, a key structural advantage lies in the spatial configuration of Indian cities, which are typically surrounded by agricultural land. This proximity enables relatively low-cost conveyance of treated wastewater to end-users. Illustratively, a city with a population of 100,000 is estimated to generate about 9-10 mld of wastewater. The utilisation of this volume for agricultural purposes would require only a limited portion of adjacent land. Even if a peripheral zone extending up to 5 km from the urban boundary is considered, allocating around 5 per cent of this area for irrigation of suitable crops, particularly non-edible or cash crops, would be sufficient to absorb the entire treated wastewater output at secondary treatment levels.
Moreover, recent developments indicate the emergence of viable reuse models, as demonstrated by initiatives in Chennai. The deployment of advanced treatment systems such as effluent tertiary reverse osmosis plants has enabled the supply of high quality treated wastewater to industrial users. In certain cases, these projects have achieved economic breakeven, reflecting a growing willingness among industries to procure treated wastewater as a substitute for fresh water. However, the scale of industrial uptake remains limited in comparison to total wastewater generation. While approximately 60 mld of treated wastewater is currently being utilised by industry, the city generates close to 800 mld, indicating a large reuse potential for other uses than what industry can support.
Looming concerns and potential solutions
The reuse of sewage sludge in agriculture is constrained by concerns related to heavy metals and pathogen content, which have limited its acceptance, particularly in urban areas. While sludge has historically been used in rural settings, regulatory and perception-related challenges persist. Notably, sludge does not qualify as a fertiliser under the Fertiliser Control Order 1985 due to its inherent characteristics, leading to resistance from the fertiliser sector. However, ongoing discussions with the Ministry of Agriculture and Farmers Welfare and other stakeholders recognise its potential as a soil conditioner. With its organic content and porosity, sludge can serve as a soil supplement and partial topsoil substitute, particularly in the context of stressed soils.
International experience, particularly from the United States Environmental Protection Agency (USEPA), provides a strong reference framework for sludge management practices. The agency’s biosolids regulations (503), developed over more than four decades of research, support the safe and extensive application of treated sludge in agriculture. In addition, pathogen management remains a key consideration in sludge reuse. The USEPA classifies biosolids into Class A and Class B categories based on pathogen levels. Class A requires significantly lower pathogen levels and therefore entails higher treatment costs. In contrast, Class B biosolids, which permit relatively higher pathogen thresholds, are widely used for non-edible applications such as cash crops, oilseeds and industrial crops, subject to defined site restrictions. In the Indian context, the emerging approach favours achieving Class B standards as a pragmatic and cost-effective benchmark for large-scale agricultural reuse. Regulatory provisions are expected to incorporate site-specific safeguards, including limited access periods, which in certain cases may be as short as 30 days.
In fact, India’s significant agricultural and forest land base offers substantial capacity for sludge utilisation. While current estimates indicate approximately 100,000 tonnes per day (tpd) of wet sludge generation, drying can reduce this to nearly 10,000 tpd. At this scale, land requirements for application remain modest relative to the total cultivated area, thereby supporting manageable and distributed reuse while mitigating concerns related to accumulation and environmental impact.
Furthermore, concerns regarding heavy metal contamination in sewage sludge have been examined through field studies conducted by the Indian Institute of Technology- Roorkee, across 22 locations. The findings indicate that heavy metal concentrations are typically low and fall well within acceptable limits under international benchmarks, particularly in smaller towns. While compliance with domestic norms may vary, the overall risk profile appears limited. In addition, parameters related to volatile activity rate, assessed through oxygen uptake measures, were also found to be within acceptable ranges. These findings suggest that with appropriate segregation of industrial effluents, sludge reuse can be undertaken with minimal environmental risk.
In sum
The policy approach actively promotes the utilisation of treated sludge within the agricultural sector, encouraging its adoption by farmers as a supplementary soil resource. In parallel, efforts are under way to develop practical, achievable and economically viable standards to facilitate the safe reuse of both sludge and treated wastewater. The objective is to ensure that treatment processes translate into effective utilisation across end-use sectors, supported by clear regulatory frameworks. This integrated approach seeks to optimise resource recovery from wastewater systems while aligning technical feasibility with economic sustainability.
Net, net, wastewater management in India is characterised by a shift from disposal-oriented approaches to resource recovery and reuse. The expansion of treatment infrastructure, coupled with evolving policy frameworks, is expected to enhance both capacity and utilisation.
India’s significant agricultural and forest land base offers substantial capacity for sludge utilisation.
