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India is a parched nation. With an annual per capita freshwater availability below the international threshold of 1,700 cubic metres (m3), India ranks 132nd in the world with respect to per capita water availability. This makes the country “water stressed”.
Between 1950 and 2024, there has been a decline of 73 per cent in per capita surface water availability in the country, as per the Union government’s India Water Resource Information System (see ‘Surface water scarcity’).
If no steps are taken to address this issue, India could become “water scarce”, when water availability drops below 1,000 m3 per capita per year.
Cities such as Delhi, Mumbai, Pune, Hyderabad and Chennai, as well as many small and medium towns, are staring at a scenario where their sources will completely run out of water. Bengaluru faced unprecedented water shortage last year. As India witnesses rapid urbanisation—most of it seemingly unplanned—the situation will get worse, especially with climate change manifesting itself as an intensification of the water cycle, resulting in frequent floods, droughts and water stress.
Reuse of wastewater is being seen as a new way of supplementing the water supply and mitigating the impending water shortage. Simply put, all used water is wastewater. Its reuse will serve the twin purpose of augmenting water resources while reducing the environmental impacts of disposing untreated wastewater.
Cities in India generate wastewater in large amounts. But most of it is not reused because management of wastewater has largely been considered from a “disposal” perspective, and not from a “reuse” point of view. According to an assessment by the Central Pollution Control Board (CPCB), sewage generation in urban centres across India was 72,368 million litres per day (MLD) for 2020-21, while the installed sewage treatment capacity was 31,841 MLD. The operational capacity, however, was 26,869 MLD, and of the total urban sewage generated, only 28 per cent (20,236 MLD) was treated. This implies that 72 per cent of the wastewater was untreated and disposed of into waterbodies or on land. This is the resource that can be utilised.
Data on urban population projections suggests that wastewater generation will increase by 75-80 per cent in the next 25 years, taking the total estimated wastewater generation to 0.13 million MLD (see ‘Wastewater projections’).
At this rate, about 0.8 billion cubic metre (BCM) of wastewater will be generated additionally every year. Thus, the total annual wastewater volume is expected to reach close to 48 BCM by 2050. This volume is about 3.5 times the existing installed treatment capacity, which underlines the need of scaling up treatment capacity and creating robust systems for wastewater collection and reuse.
The Union Ministry of Jal Shakti has mandated that cities must recycle and reuse at least 20 per cent of the water they consume. As per the NITI Aayog Composite Water Management Index, states are demonstrating progress in water management, but the overall performance is well below adequate: 80 per cent of the states assessed in 2017-19 have shown improvement in their water management scores, with an average improvement of +5.2 points. But 16 states of India still score less than 50 points out of 100 on the index, and fall in the low-performing category. These 16 states account for 48 per cent of the population, 40 per cent of the agricultural produce, and 35 per cent of the economic output of India.
Over the past few years, Delhi-based non-profit Centre for Science and Environment (CSE) has undertaken a comprehensive analysis of 35 case studies across 16 cities in seven states and Union Territories—Delhi, Rajasthan, Haryana, Uttar Pradesh, Maharashtra, Tamil Nadu and Karnataka—to explore the status of wastewater management in the country (see ‘Policy status’).
The primary aim of the study is to present an assessment of what the country is doing to reuse treated wastewater, the challenges, what is working and what is not, and why. The field visits concentrated on reuse of treated used water, while the desk research focused on assessing the extent of water reuse adoption in urban areas and the government initiatives supporting these practices.
Findings of the study, published in the report “Waste to Worth: Managing India’s Urban Water Crisis Through Wastewater Reuse”, cover the policies, programmes and on-ground practices while providing valuable insights to policymakers and practitioners. The study only concentrates on the reuse of treated wastewater from centralised treatment facilities, not decentralised treatment facilities at household, institution or community levels. It also outlines recommendations for different reuse sectors such as agriculture, industry and construction. Here’s a look at the key findings…
Total wastewater/ sewage generated: 3,600 MLD
Total wastewater/ sewage treatment capacity: 3,033 MLD
Total wastewater/ sewage treatment being treated: 2,587 MLD
Wastewater being reused: 49%
Recommended reuse: Lake recharge, thermal power plant, horticulture
Delhi has limited internal water resources and is largely dependent on external resources—the Ganga (via upper Ganga Canal), Yamuna, Ravi and the Beas (via the Bhakra dam storage)—over which it exercises no direct control and is always under pressure from upper and lower riparian states. In 2019, the Delhi Jal Board (DJB) produced just 74 per cent of the water demand of 4,770 MLD.
The extensive water supply and use in Delhi leads to the generation of a large volume of wastewater. Delhi is equipped with 37 sewage treatment plants (STPs) that have a combined capacity of 3,033 MLD. Presently 2,587 MLD of this capacity is being utilised. Considering Delhi’s escalating water demands and constraints on the availability of water resources, the reuse of treated water for non-potable purposes is a good strategy to bridge the gap.
Delhi reuses 666 MLD of treated wastewater of which 409 MLD is used for horticulture in parks, 159 MLD in development or rejuvenation of lakes or waterbodies and 98 MLD by Delhi’s Irrigation and Flood Control Department for horticulture/farming. DJB has proposed that about 357 MLD of treated wastewater should be used for groundwater recharge at the wetland near coronation pillar and for Bhalswa lake recharge in Jahangirpuri. The remaining 332 MLD treated STP water can be reused for development or rejuvenation of lakes. The co-location of STPs with lakes and parks has been undertaken to assess potential reuse demands and formulate plans.
The Draft Water Policy, 2016, of Delhi-National Capital Territory has made a good effort at decentralising the reuse of treated wastewater and setting targets. The action plan focuses on the revival of lakes, waterbodies and parks for augmenting water supply through groundwater recharge from the treated wastewater. However, in case of this kind of reuse, the quality of treated water should be high. Currently, 21 of the 37 STPs do not comply with the Delhi Pollution Control Committee norms.
Delhi-National Capital Region has 11 thermal power plants. The reuse of treated water in thermal power plants is mandated under the policy but Delhi has no stated plans to use the treated water for thermal power plants.
Total wastewater/ sewage generated: 1,551 MLD
Total wastewater/ sewage treatment capacity: 1,299 MLD
Total wastewater/ sewage treatment being treated: 956 MLD
Amount being reused: 29%
Recommended reuse: Agriculture, lake recharge, industry
Rajasthan can be considered a water-deprived state, with an average annual per capita availability of less than 800 m3. There is a 30 per cent disparity between water demand and supply in the state, which is heavily dependent on groundwater for irrigation. About 90 per cent of the drinking water and 60 per cent of the irrigation water is sourced from groundwater supplies in Rajasthan. According to the latest report submitted to the National Green Tribunal (NGT) by Rajasthan, 1,551 MLD of sewage is generated in the state. There are 118 STPs in operation in the region. Currently, 956 MLD of the total 1,299 MLD capacity is being utilised for treating sewage, leaving a gap of 343 MLD. This shows that about 61 per cent of sewage is being treated.
Furthermore, 13 STPs with a total capacity of 179 MLD are not compliant with CPCB norms. Of the total installed capacity in the state, Jaipur alone accounts for 40 per cent, with 19 STPs that have a collective capacity of 512 MLD. Other major cities like Jodhpur, Kota and Bikaner, also contribute significantly to the state’s sewage treatment capacity. Keeping in mind the volume of treated wastewater, Rajasthan has a high potential for reusing treated water.
Rajasthan, as of now, is reusing 29 per cent of the treated wastewater. The state lacks a comprehensive policy for the reuse of treated water but has a brief action plan. However, there appears to be a lack of implementation of the action plan and adherence to timelines on the ground. It is necessary to develop city-specific action plans. A significant portion of treated wastewater in Jaipur and other cities is reportedly reused for agriculture, mainly due to the presence of canal systems. However, this practice is largely informal. In contrast, industries such as cement, iron and zinc, which require large amounts of water, have established more formalised methods to secure their rights to treated water reuse, particularly in areas where fresh water is scarce.
The public-private partnership (PPP) model has played a role in securing fresh water sources in Rajasthan. However, it has also led to industries monopolising and privatising the reuse of treated water. The decision on whether this practice is appropriate should be made by state and city authorities, considering the water needs for other essential purposes within the state and city based on equity and justice. The quality of the treated water is also an issue. A total of 13 STPs in the state are not compliant with CPCB norms. In locations where treated water is used for industry, STPs maintain discharge standards suitable for industrial applications. But in cities like Jaipur, the quality of treated sewage is often highly questionable.
Total wastewater/ sewage generated: 1,655 MLD
Total wastewater/ sewage treatment capacity: 1,965 MLD
Total wastewater/ sewage treatment being treated: 1,373 MLD
Amount being reused: 15.09 %
Recommended reuse: Agriculture, industry, construction, lake recharge
Haryana aims to reuse 80 per cent of treated water by 2030. Agriculture is planned to consume 85 per cent of reused treated water in the state, with the Integrated Water Resources Action Plan (IWRAP), 2023-25, focusing on utilising treated water from 177 STPs for micro-irrigation and agriculture. Challenges to the reuse of treated water include non-compliance of STPs with CPCB norms, slow state-wide project progress, and the need for monitoring to prevent untreated sewage mixing.
In 2021, Haryana’s overall water demand was estimated to be 95,788 MLD while the total water availability from all sources was 57,358 MLD, showing a demand- supply gap of 38,430 MLD. According to a report submitted by the Haryana government to the NGT in November 2023, the estimated sewage generation in Haryana is 1,655 MLD. The state has 180 STPs with a combined treatment capacity of 1,965 MLD. All the STPs are operational, and 1,501 MLD of the total capacity complies with the discharge norms. Of the 1,965 MLD total installed capacity, only 1,373 MLD is actually being utilised. Although the total installed treatment capacity exceeds the total sewage generated in the state, in Faridabad and Gurugram, there is a gap of 232.5 MLD and 93 MLD, respectively, between the sewage generated and the treatment capacity. Twelve STPs with a total capacity of 300 MLD are currently being constructed, and 11 new STPs with a total capacity of 444 MLD have been proposed.
Through IWRAP, the state aims to save water through demand-side interventions (micro-irrigation, crop diversification, direct seeded rice, conservation tillage and water efficiency) as well as supply-side measures (underground pipelines for irrigation, lining canal water courses, groundwater recharge, rejuvenation of ponds, reuse of treated water and increasing surface water storages). These interventions aim to reduce the existing water gap by more than 49 per cent in 2023-25, instead of the three years as proposed in the earlier action plan.
According to IWRAP, only 15.09 per cent of the 1,130 MLD treated sewage is being reused for non-potable purposes in agriculture, horticulture, construction and the industrial sectors. Only a few of the big districts are reusing treated wastewater. For example, Gurugram, which accounts for nearly 50 per cent of the total treated water generated in Haryana is reusing the highest amount (47 per cent), followed by Kurukshetra (35 per cent), Panchkula (34 per cent), Sonipat (31 per cent), Faridabad (25 per cent), Jhajjar (14 per cent) and Rewari (5 per cent). At other places, treated wastewater is directly discharged into drains.
Overall, while Haryana reuses only 15 per cent of its treated wastewater, the state policy aims to increase the usage to 80 per cent by 2030. The State Action Plan mandates 56.7 per cent reuse of treated water in the state by March 2025 and 54.3 per cent by December 2028.
Total wastewater/ sewage generated: 5,550 MLD
Total wastewater/ sewage treatment capacity: 4,176 MLD
Total wastewater/ sewage treatment being treated: 3,296 MLD
Amount being reused: NA
Recommended reuse: Agriculture, industry
Uttar Pradesh possesses a significant volume of sewage water, which, if treated, could be efficiently repurposed to cater to the specific needs of urban areas while also sustaining river flow. The state’s 762 towns generate 5,500 MLD of sewage, of which 3,296 MLD is treated in 139 STPs. For its study, CSE visited 16 STPs in Uttar Pradesh, prioritising its large and medium towns.
Earlier, the Uttar Pradesh state policy framework on water prioritised groundwater use management. From 2020, the focus has shifted to the reuse of treated waste water from its STPs. But still, the reuse of treated water is not widely practised in the state. Around 50 per cent of the total installed capacity is concentrated in five major cities—Lucknow, Kanpur, Prayagraj, Ghaziabad and Varanasi. As a result, most water reuse initiatives are concentrated within these urban centres and their surrounding districts. The treated water is predominantly utilised in agriculture, either through planned or unplanned methods, often integrated with the existing canal system in Uttar Pradesh.
The state has no mandated policy or action plan on the reuse of treated wastewater. As a result, major cities like Lucknow and Kanpur, along with large STPs, face challenges in reusing treated wastewater and there is a pressing need for the same along with city-level action plans. Given that the primary reuse of wastewater in Uttar Pradesh is for agriculture, there is a critical need for the implementation of monitoring mechanisms to track both quantity and quality. Third party oversight is essential to ensure the safety and health of end-users.
Total wastewater/ sewage generated: 3,357 MLD
Total wastewater/ sewage treatment capacity: 2,677 MLD
Total wastewater/ sewage treatment being treated: 2,054 MLD
Amount being reused: 43%
Recommended reuse: Industry, lake recharge
Karnataka faces significant water stress, particularly in its drought-prone regions, and in Bengaluru that depends almost entirely on water supply from the Kaveri river to meet its growing water needs. Rural Karnataka relies on lakes, tanks and other minor surface irrigation structures to meet the water demand. In urban areas, demand for domestic water consumption is projected to nearly double by 2030 from 2011 levels. To cope with this, citizens have resorted to private arrangements that are largely dependent on groundwater extraction. This has resulted in excessive groundwater depletion in several large- and medium-sized cities.
According to the latest report submitted by the state to NGT, 3,356.5 MLD sewage is generated in Karnataka by its 281 towns. There are 177 STPs with a treatment capacity of 2,676.51 MLD. Currently, only 2,054 MLD (77 per cent) of the installed capacity is being utilised for treating sewage.
The state’s urban wastewater reuse policy of 2017 mandates 10 major cities to prepare plans and embrace wastewater reuse by 2020 and extend this to 100 per cent for all major cities or towns by 2030. The policy also targets 20 per cent reuse of treated sewage and to be increased to 50 per cent by 2030. But a clear action plan or timeline at the state level is missing.
Karnataka has taken steps towards promoting decentralised STPs at the household level in Bengaluru. The state has a well-defined reuse policy for treated wastewater. The regulations mandate apartment complexes above 50 units, and commercial and institutional buildings with more than 2,000 sq m to have an STP on site and the sale of 50 per cent of the treated wastewater from apartments for non-potable uses, creating a wastewater market that could potentially meet 26 per cent of the city’s water demand.
Fifty per cent of the total installed sewage treatment capacity of the state is present in Bengaluru itself and therefore the maximum opportunity to reuse the treated water lies in this city. Keeping in view the water scarcity in Bengaluru, it is crucial for the city to explore opportunities to address its recurring water scarcity.
Of the total 1,193 MLD of treated wastewater in the state, 825 MLD is currently being reused for purposes such as lake revival, industrial use and irrigation in Bengaluru and nearby water-scarce districts. The water parched districts of Kolar and Chikkaballpur have benefitted immensely by the Koramangala-Challaghatta Valley and Hebbal-Nagawara Valley projects. Apart from this, decentralised sewage treatment systems in the city have been supplying treated used water to parks and gardens and, to some extent, industries.
The primary focus of treated water reuse is directed towards lake recharge, constituting 75 per cent of the total, while the remaining 25 per cent is allocated to agriculture, industry and horticulture, with industrial reuse being the least prominent. Bengaluru has a high potential for reusing treated water in the construction industry which is still an unexplored area in the city.
Total wastewater/ sewage generated: 3,938 MLD
Total wastewater/ sewage treatment capacity: 2,349 MLD
Total wastewater/ sewage treatment being treated: 1,093 MLD
Amount being reused: 17%
Recommended reuse: Industry, lake recharge
Tamil Nadu is a highly urbanised and industrialised state. Its 528 towns generate 3,938 MLD sewage of which 1,093 MLD is treated. A total of 17 per cent of the total treated wastewater is reused, of which Chennai alone accounts for 58 per cent of the total reuse.
Each year, Tamil Nadu experiences a cycle of extreme weather, swinging from monsoon floods to summer water shortages to cyclones. Chennai, in particular, endures alternating periods of water scarcity and flooding, exemplified by its “Day Zero” declaration in 2019 following two years of insufficient monsoon rainfall and subsequent reservoir depletion. It is crucial for the state to promote the reuse of treated wastewater to augment its water supply, prioritised for drinking water, followed by shallow aquifer recharge and agriculture. A clear action plan and timeline is missing for the state in policy. The Chennai Metropolitan Water Supply and Sewerage Board (CMWSSB) is undertaking PPP model-based tertiary treated water supply for industries. (Tertiary treatment is an advanced cleaning process that involves additional filtration, chemical treatment and disinfection to remove remaining contaminants, nutrients and pathogens, producing water that is suitable for reuse or safe discharge into the environment). The cost incurred for tertiary treated water reuse is high and it automatically limits demand to the industrial sector that can pay for it.
Secondary treated water reuse cost is much lower and should be promoted for addressing groundwater recharge through tanks, lakes and waterbodies. (Secondary treatment involves biological processes to remove dissolved and suspended organic matter from wastewater. This stage significantly reduces the organic load and prepares the water for further purification). Currently, even lake revival is being done using tertiary treated water. The ambition was to scale up to 260 MLD by 2024. This has not occurred within the expected time frame.
A state policy that prioritises groundwater recharge through tanks and lakes, with treated wastewater from STPs, guided by principles of equity and justice is needed for Tamil Nadu. If the state is able to treat and reuse treated water by even 20 per cent of its total sewage generation (3,938 MLD), it could augment water supply for its cities. The reuse potential from the centralised treatment facilities will be limited in the coastal cities like Chennai owing to the natural slope and terrain.
Total wastewater/ sewage generated: 10,547 MLD
Total wastewater/ sewage treatment capacity: 7,411 MLD
Total wastewater/ sewage treatment being treated: 4,317 MLD
Amount being reused: 17%
Recommended reuse sectors: Agriculture, construction, thermal power plants
Nearly 42.5 per cent of Maharashtra’s geographical area is water-stressed and there is an urgent need to supplement the fresh water sources by reuse of treated wastewater, particularly in the urban areas. The state has 414 urban local bodies that generate 10,547 MLD of sewage. There are 147 STPs in operation with a combined treatment capacity of 7,411 MLD. Currently 4,317 MLD capacity is being utilised for treating the sewage. The two case studies covered in the study—Pune and Nagpur—accounts for 17 per cent reuse of the total treated water in the state.
The reuse of treated wastewater is primarily concentrated in three or four major cities such as Nagpur, Pune and Mumbai, and has not been extensively adopted in other parts of the state. Currently, the majority of treated wastewater in Mumbai is discharged into the sea after ensuring that it meets the required quality standards. The reuse possibility is limited because of Mumbai’s status as a coastal city. Due to its natural slope and terrain the infrastructural development of supplying treated water against the slope will be immensely challenging and cost-intensive. Hence, the Municipal Corporation of Greater Mumbai has adopted a programme to decentralise wastewater treatment.
In cities where sewage generation is lower, treated water can be utilised for recharging shallow aquifers. It can also be used for the revival of waterbodies and lakes. Hence, each city should have their own action plan for the reuse of treated water while keeping local demand in mind The Maharashtra State Water Policy, announced in 2019, advocates for the reuse of treated wastewater as part of water use efficiency and conservation. Despite having provisions for the reuse of treated water in the state, as mentioned in the notification of the Maharashtra Water Resources Regulatory Authority, 2019, the reuse of treated water has not been widely practised in the state as it lacks a clear operational and implementation mechanism.
The Maharashtra State Water Policy also mandates penal action for the polluter of water resources. Despite this, many STPs have not been compliant with the standards. For example, all the nine STPs in Pune have not been complying with the discharge standards. In total, 80 STPs have not been complying with the CPCB norms in the state.
The PPP model in Nagpur for securing water for operating thermal power plants showcases how partnerships and initiatives can lead to the optimal utilisation of resources. But these kinds of models may not be feasible for smaller cities. The major focus of reusing treated wastewater in the industry will require tertiary treated water which is capital intensive and often hinders the scaling up of secondary treated water which is easier to uptake. The focus should be to increase the uptake of secondary treated water by exploring demands to achieve the target at a faster pace.
Evolution of national policies and programmes promoting and mandating reuse of treated wastewater
2008
National Urban Sanitation Policy: Promotes the recycle and reuse of wastewater. The policy mandates that treated wastewater should comprise a minimum of 20% of the water used in a city.
2010
Service-Level Benchmark Framework: Encourages the reuse of wastewater in cities.
2012
Jawaharlal Nehru National Urban Renewal Mission (JNNURM): Mandates treatment of 100% wastewater in 63 cities, promotes reuse of treated wastewater.
National Water Policy (NWP), 2012: Focuses on reducing water pollution; the draft of the revised NWP, 2020, embraces the imperative of recycling and reuse.
2013
Central Public Health and Environmental Engineering Organisation (CPHEEO) Manual on Sewerage and Sewage Treatment Systems: Provides technological options and norms for treated sewage quality for specified activities.
2014
Namami Gange-National Mission for Clean Ganga (NMCG): Includes initiatives for treatment of sewage and industrial effluents, with emphasis to promote reuse of treated wastewater.
2015
Atal Mission for Rejuvenation and Urban Transformation (AMRUT): Encourages reuse of wastewater.
Namami Gange: Memorandums of Understanding signed by NMCG with the Union power, railways and agriculture ministries for reuse of treated wastewater.
2016
Power Tariff Policy: Mandates thermal power plants to use treated sewage water within 50 km of sewage treatment plants.
2017
National Faecal Sludge and Septage Management (FSSM) Policy: Focuses on leveraging FSSM to achieve 100% access to safe sanitation.
2019
Central Pollution Control Board (CPCB) issues guidelines for use of treated effluent in irrigation.
2021
Swachh Bharat Mission (SBM) 2.0: Aims to ensure no untreated wastewater is discharged into environment, and recommends utilisation of used water as much as feasible, but not less than 20%.
AMRUT 2.0: Mandates that all cities with a population of more than 0.01 million recycle used water to meet 20% of the city’s water demand and 40% of the industrial water demand at the state level.
2022
National Framework on Safe Reuse of Treated Wastewater: A guiding document for states to formulate reuse water policies and implement them in a time-bound manner. A draft policy template also developed to aid in states’ policy preparation.
2024
CPCB releases national draft guidelines on reuse of treated sewage, which emphasises sectoral prioritisation with certain standards.
This article was originally published as part of Down To Earth’s 16-31 March 2025 print edition