About 30% of people in India live in cities that are expected to double in population by 2050. Annual per capita water availability is expected to decline to 1,140 cubic meters by 2050, from 1,545 cubic meters in 2011. With a growing economy and changing lifestyles the pressure on already strained water resources is increasing. Most cities in India are water stressed, with no city having 24/7 water supply. According to the Ministry of Urban Development (MoUD), 182 cities require immediate attention in regards to proper water and wastewater management. The coverage of sanitation has increased but resource sustainability and slippages are very common in that coverage. Moreover, in cities with more than one million people, the official water supply after 35% loss in leakages is just 125 litres/day per capita which is considerably lower than the demand of 210 litres/day per capita. Infrastructure development and regulations have not kept pace with population growth and urbanization and as a result wastewater management has become a major challenge. Government has made significant efforts to reduce surface water pollution but they remain jeopardized by the lack of wastewater treatment. An estimated 160 million latrines and septic tanks contribute to 80% of the pollution of the national surface waters. There is also major groundwater exploitation in urban India as many towns and cities depend on groundwater for their supply. Reform is needed which reduces non-revenue water, groundwater exploitation, considers waste as a resource, and looks at the water cycle in a holistic way.
Urban water security through a holistic approach implies managing water resources and its waste in a new integrated way, with a focus on considering the whole urban water cycle as one system within the watershed, aiming for water security through diversity and optimum use of all potential sources of water and matching water quality with purpose of use, aiming for a better utilization of natural systems for water and wastewater treatment, considering storm water/rainwater catchment systems as a potential source, better managing use of water, effluents and water demand and hygiene behavior, strengthening leakage management and maintenance, strengthening resilience of urban water systems that are facing drought or floods. Wastewater is a resource that can be used productively. Grey water can be reused for irrigation, urban agriculture and industrial processes, treated or untreated depending on the purpose of its use and its legislation; nutrients in wastewater (grey and black) can be used for energy production and fertilizer production.
Wastewater disposal and treatment is a very major problem in most Indian cities. Non-collection of wastewater and discharge of untreated wastewater into low-lying areas or various water bodies causes sever water and land pollution problems. This situation reduces the availability of usable water for water supply. Wastewater generation is calculated at a minimum of 80 per cent of water supplied. However, since people use their own sources of water, additional amounts of wastewater may be generated. Wastewater collection in most urban centers with sewerage system usually does not exceed about two-thirds of that generated. However, the wastewater treatment situation is quite alarming. While the smaller sized urban centers with sewerage system treat less than one-fourth of the wastewater generated, even the metropolitan cities treat only about two-fifths of the wastewater generated. Wastewater disposal is done both on land and in water body by most urban centers. Proximity to water body, local conditions and financial constraints determine the place and method of wastewater disposal. Recycling/reuse of wastewater is practiced in very few urban centers and wherever it is done, it is mostly used for agriculture or horticultural purposes. Recycling/reusing wastewater will reduce the demand for fresh water, thereby also postponing the capital investment requirements for water augmentation.
Surface water and groundwater are the sources of India’s water supply. Other sources, such as desalination, are negligible because they are not cost effective.
Figure 2: Surface Water, Groundwater Over Time
Source: World Bank Report on Water in India Surface Water
The main rivers, the Ganges, Bramhaputra, Mahanadi, Godavari, Krishna, Kaveri, Indus, Narmada, and Tapti, flow into the Bay of Bengal and Arabian Sea.They can be classified into four groups: Himalayan, coastal, peninsular, and inland drainage basins. The Himalayan Rivers, such as the Ganges, are formed by melting snow and glaciers and therefore have a continuous flow throughout the year. The Himalayas contain the largest store of fresh water outside the polar ice caps, and feed seven great Asian rivers. This region receives very heavy rainfall during the monsoon period, causing the rivers to swell and flood. The coastal rivers, the Bramhaputra and the Krishna, especially on the west coast, are short in length with small catchment areas. The peninsular rivers, which include the Mahanadi, Godavari, Krishna, and Kaveri, flow inland and also greatly increase in volume during the monsoon season. Finally, the rivers of the inland drainage basin, such as the Mahanadi and the Godavari, dry out as they drain towards the silt lakes such as the Sambhar, or are lost in the sands.
India receives an average of 4,000 billion cubic meters of rainfall every year.Unfortunately, only 48% of rainfall ends up in India’s rivers. Due to lack of storage and crumbling infrastructure, only 18% can be utilized. Rainfall is confined to the monsoon season, June through September, when India gets, on average, 75% of its total annual precipitation. Once again, due to India’s storage crunch the government is unable to store surplus water for the dry season. Such uneven seasonal distribution of rainfall has not stimulated the development of better capturing and storing infrastructure, making water scarcity an unnecessary yet critical problem.
Groundwater is the major source of drinking water in both urban and rural India. It is also an important source of water for the agricultural and the industrial sectors. India possesses about 432 bcm of groundwater replenished yearly from rain and river drainage, but only 395 bcm are utilizable. Of that 395 bcm, 82% goes to irrigation and agricultural purposes, while only 18% is divided between domestic and industrial. Total static groundwater available is approximately 10,812 bcm.
Groundwater is increasingly being pumped from lower and lower levels and much faster than rainfall is able to replenish it. The average groundwater recharge rates of India’s river basins is 260 m3/day. The Delhi Jal Board, which is responsible for supplying potable water, estimates that water tables are dipping by an average of 0.4 meters a year. In addition, the human, agricultural, and industrial waste that pollute India’s rivers seep into the ground, thus contaminating the groundwater. Groundwater crisis is not the result of natural factors; it has been caused by human actions. During the past two decades, the water level in several parts of the country has been falling rapidly due to an increase in extraction. The number of wells drilled for irrigation of both food and cash crops have rapidly and indiscriminately increased.