How effective management of wastewater helps address India’s water crisis

Rapid urbanisation, industrial expansion and population growth have driven up the demand for clean water, while climate change and erratic rainfall patterns have further strained availability. Between 1951 and 2024, there has been a decline of 73 per cent in per capita surface water availability in the country.

The rising water scarcity across the world has drawn attention to wastewater treatment and reuse. In India, the water and wastewater sector, particularly the reuse of treated wastewater, has recently gained attention, especially in water-stressed urban areas. 

According to the Central Pollution Control Board, Indian cities generate over 72,000 million litres per day (MLD) of sewage, but the installed treatment capacity is less than 32,000 MLD. Only 28 per cent of urban wastewater in India is treated, while the remaining 72 per cent flows untreated into water bodies and land. 

If properly managed, wastewater can serve as a valuable resource to bridge the gap between water demand and supply. A critical challenge in this context is the management of wastewater, particularly in urban areas. 

Sources and impact of wastewater

Wastewater in India primarily originates from multiple sources, the most significant being domestic sewage, industrial effluents, and agricultural run-off. Domestic sewage constitutes the largest share, which flows directly into rivers and lakes. For example, Yamuna receives 641 million litres of untreated sewage per day, turning the river ecologically dead.  

Industrial discharges add another layer of pollution. According to the Pollution Control Board’s Data, there are 3,519 highly polluting industries in the country that discharge wastewater into India’s rivers. The Ganga basin is highly affected due to industrial pollution with tanneries in Kanpur and distilleries in Bihar being major sources. These effluents often contain heavy metals, dyes, and toxic chemicals, posing long-term risks to human and ecological health.  

Agricultural run-off is also a critical source of nutrient pollution that causes eutrophication (the process of water enrichment with excess nutrients, primarily phosphorus and nitrogen) in water bodies. For instance, the Vembenad lake in Kerala, a Ramsar Site, has witnessed a declining fish population due to nutrient pollution. 

Wastewater is not only an environmental issue, but a serious public health concern too. From a public health perspective, contaminated water is a major source of waterborne diseases such as diarrhoea, cholera and dysentery and has been linked to the spread of anti-microbial resistance. Around 37.7 million Indians are affected by waterborne diseases annually. It also increases the cost of potable water treatment and affects livelihoods dependent on clean water, such as fisheries and tourism.

Legal and institutional framework

India has developed an extensive legal and institutional framework for wastewater management, although implementation remains uneven. The Water (Prevention and Control of Pollution) Act, 1974 was the first comprehensive legislation aimed at preventing and controlling water pollution. It established central and state pollution boards, and empowered them to set effluent standards, monitor compliance, and take corrective action. The Central Pollution Control Board (CPCB) issues guidelines on the treatment of wastewater, especially sewage water. 

At the policy level, the National Water Policy, 2012 has stressed integrated water resource management and explicitly recognised the need for wastewater recycling and reuse. Several policy initiatives have also been taken to tackle river pollution, the most notable being the National Mission for Clean Ganga or the Namami Gange programme, along with other river rejuvenation programmes aimed at restoring polluted river stretches identified by CPCB. 

Flagship programmes like Swachh Bharat Abhiyan, AMRUT and the Smart Cities Mission also promote wastewater reuse facilities in urban areas. These initiatives combine infrastructure development for sewage treatment with efforts at public participation and institutional coordination. However, their impact has been constrained by gaps in enforcement, inadequate operation, and maintenance of treatment plants and fragmented governance. Only 11 out of 28 states have formulated wastewater reuse policies, and most lack clear roadmaps for implementation. 

More recently, the Draft Liquid Waste Management Rules, 2024 were notified under the Environment Protection Act, 1986. It outlines measures to minimise waste generation, establish proper collection systems, ensure effective treatment, and promote the reuse or utilisation of treated wastewater and sludge. The draft rules align with the circular economy approach by promoting wastewater as a resource rather than a liability. However, achieving these objectives requires stronger institutional capacity, sustainable financing models and effective monitoring mechanisms.

Evolving technological interventions

That apart, wastewater treatment in India relies on a combination of conventional and advanced technologies, each with distinct advantages and limitations. One of the most used conventional methods is the Activated Sludge Process (ASP). It is a common aerobic method involving removal of suspended solids and organic contaminants through the activity of microorganisms such as bacteria, fungi and algae. However, high energy requirements and maintenance remain the critical challenges in this method. 

The Sequential Batch Reactor (SBR) is an advanced wastewater treatment process that operates in batch mode through sequential phases. Although it requires continuous monitoring, its operational flexibility makes it one of the highly used methods in sewage wastewater treatment applications. Another popular sewage treatment technology is the Up-flow Anaerobic Sludge Blanket (UASB), which is low-cost and energy-efficient. However, most of these conventional methods are less effective in handling complex industrial effluents and require a large space to operate.

There are advanced technologies like the Membrane Bioreactor (MBR), which integrates biological treatment with membrane filtration and produces high-quality effluent suitable for reuse in industrial and non-potable applications. Although its high installation and maintenance cost remains the major obstacle, it is a suitable choice for industrial areas and high-value urban areas where the benefits of reuse outweigh the costs. Emerging nano-technologies such as nano filters show promise in enhancing treatment efficiency, though they are still at an experimental stage in India.

What is the way forward? 

While India generates vast quantities of wastewater, it does not have a comprehensive national mandate for wastewater reuse. The draft Liquid Waste Management Rules 2024, once operationalised, hold potential to standardise the treatment process and encourage reuse.

Technological interventions, particularly SBRs and MBRs, have shown promise in improving treatment efficiency and effluent quality, though their adoption needs to be tailored to India’s economic and infrastructural realities. 

Public-private partnerships can also play a crucial role in financing and operating advanced treatment infrastructure. Alongside the latest technologies, nature-based and decentralised solutions, such as constructed wetlands, waste stabilisation ponds, and decentralised treatment plants, are being explored as cost-effective alternatives, particularly suitable for peri-urban and rural areas. 

In addition to this, awareness is essential to overcome social resistance and build public trust in the safe use of treated wastewater, particularly for agricultural and non-potable uses. Ultimately, an integrated approach combining strong regulation, advanced technologies and promotion of water reuse will be essential for making wastewater management not just an environmental mandate but also a resource recovery opportunity for India’s future.

Post read questions

What are the major sources of wastewater in India? Evaluate major programmes and policies for wastewater treatment and reuse.

Compare the conventional wastewater treatment methods like Activated Sludge Process (ASP) and Up-flow Anaerobic Sludge Blanket (UASB) with advanced technologies such as the Membrane Bioreactor (MBR) for treating complex industrial effluents?

What are the key challenges limiting the success of programmes like Namami Gange and AMRUT in wastewater management?

Why is public trust and awareness critical for promoting wastewater reuse in agriculture?

What integrated approach would you recommend for India to overcome its wastewater management challenges?

(Renuka is a Doctoral researcher at the Himachal Pradesh National University, Shimla.)

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