Abstract:
Freshwater is an inimitable natural source with fascinating qualities. Worldwide availability of clean water is deficient as its demand has increased three folds since 1950s mainly in countries of African, Middle Eastern and South Asian regions (Gleick, 2003). Amongst major water consuming segments, agriculture ranks at the top, sharing for nearly 85% of worldwide utilization (Jury and Vaux, 2007). Several millions people are likely to face challenge of severe water scarcity associated with global warming in future. Around 92% total land in Pakistan constitutes arid or semi arid areas where the availability of water is naturally insufficient. Pakistan has not been blessed with ample water resources to meet the irrigation requirements of agricultural lands (Tahir et al., 2011). About 27% of the total geographic area is under cultivation in Pakistan. In Punjab, total area under crop production is 57% of total cultivated area (Rehman et al., 2013). Vegetables are annually grown on an area of 253,800 hectares in Pakistan (Perveen et al., 2010).
There are several contributing factors leading to water shortage in Pakistan including poor distribution systems of irrigation, salty ground water, rapid population growth and frequent drought conditions. This situation has lead to the application of untreated city waste water for irrigating agricultural lands which has now become a common and prevalent practice in Pakistan (Khalil and Kakar, 2011) especially in peri-urban areas and in many other developing countries of the world (Ensink et al., 2004a; Sharma et al., 2007; Nagajyothi et al., 2009; Nath et al., 2009).
