ABSTRACT
Introduction Pollution abatement strategies for water resources in India and other developing countries have given priority to point sources of pollution (Banadda et al. 2009; Ongley 1996). However, it is increasingly becoming evident that improvement of the quality of surface and groundwater will also require the control of pollution from nonpoint sources (NPS) (Ribaudo 1992).1 Controlling NPS pollution is particularly crucial in rural areas where groundwater is an important source of drinking water. Groundwater nitrate (NO3) concentration can be considered as an indicator of NPS pollution (Engel et al. 1996). In several parts of India, growing access to irrigation facilities along with unbalanced use and overuse of nitrogenous fertilizers, unlined and open storage of livestock wastes, and insanitary disposal of human wastes have led to high concentrations of NO3 in groundwater. There is limited information on the level of pesticide contamination of water sources. However, information on the level of NO3 in groundwater as well as surface water across Indian States is available to some extent. In India, 85-90 per cent of the rural population depends on groundwater for drinking purposes (DDWS 2008). Consumption of NO3-contaminated drinking water poses various short-and long-term health hazards to various age groups (WHO 2004). NO3 concentration in water used for drinking should be less than 50 mg/l (milligram per litre) (WHO 2004). In India, according to the Bureau of Indian Standards (BIS 1991), the maximum acceptable limit of NO3 in drinking water is 45 mg/l (which is equivalent to 10 mg/l of NO3-N, nitrate-nitrogen). However, the maximum permissible limit of NO3 is set at 100 mg/l, provided there are no alternative source(s) of drinking water (BIS 1991). Access to safe drinking water is vital for human well-being (UNDP 2006). One of the targets of the United Nations’ Millennium Development Goals (MDGs) is to ‘halve by 2015 the proportion of people without sustainable access to safe drinking water and basic sanitation’ (Target 10). Pollution from NPS makes groundwater resources unsuitable for drinking. Thus the environmental sustainability of safe sources of drinking water for future generations is at stake. People exposed to polluted drinking water are vulnerable to various water borne
diseases. It is primarily the poor and marginal section of the population who suffer the most, as they cannot afford to protect themselves from the impacts of pollution. Costs associated with mortality and morbidity of water-borne diseases are high. For example in India water-borne diseases annually put a burden of US$3.1 billion to US$8.3 billion in 1992 prices (Brandon and Hommann 1995). A recent study conducted by the Water and Sanitation Programme of the World Bank estimates that the total economic impacts of inadequate sanitation in India amounts to Rs.2.44 trillion (US$53.8 billion) a year – this is equivalent to 6.4 per cent of India’s GDP in 2006 (Water and Sanitation Programme undated). In India, water supply authorities mostly prefer curative measures (e.g. ex post treatment or source substitution) at a higher incremental cost of water supply as compared to precautionary measures (e.g. ex ante protection of drinking water sources). Therefore, major challenges that the rural water supply sector in India is facing today are not only to meet the large investment requirement to augment the water supply, but also an additional investment burden to tackle the water quality related problems. This has led to an astronomical demand for investment in infrastructure to supply drinking water to the rural populace (Mukherjee 2008). For example, release of funds by the Department of Drinking Water Supply (DDWS), Government of India (GoI), under the Accelerated Rural Water Supply Programme (ARWSP) has gone up from Rs.1,440 crore in 1998-99 to Rs.7,056 crore in 2008-09, which shows a 390 per cent increase (DDWS 2008). The DDWS has allocated Rs.735.67 crore during 2006-07 to tackle water quality related problems under ARWSP, which is 21 per cent of the total release of funds under ARWSP for the year (i.e. Rs.3,532 crore). According to the estimate released by the Rajiv Gandhi National Drinking Water Mission on 31 March 2004, in India 13,958 habitations are affected by drinking water affected by NO3 pollution. The number of NO3-affected habitations has gone up from 4,003 as on 1 April 1999 to 19,387 as on 1 April 2006.
