Two in every ten people in the developing countries do not have access to clean drinking water (FAO 2003). As of 2002, nearly 700 million people still lacked access to clean water in the Asian and Pacific (ASPAC) region. In spite of worldwide water scarcity, irrigated agriculture accounts for three-quarters of world water withdrawals from both surface and ground water, and 85 percent of the consumption of water withdrawn is in developing countries. Irrigated agriculture will be responsible for nearly 80 percent of the total increase in crop production in Asia over the next three decades (FAO 2003). However, the agriculture sector in Asia is expected to fiercely compete for water not only with human consumption, but also with the industrial sector. The deterioration of agricultural water quality has rapidly proceeded with the vast increase in Asian population accompanied by urbanization, with water resources being contaminated with a variety of hazardous chemicals and virulent pathogens. These pollutants have been caused mainly by untreated human excreta and garbage due to the lack of sanitation, animal and industrial waste, agrochemicals, and various other sources associated with increased agricultural activities to meet people's demand in terms of quantity and quality improvement of agricultural produce and food diversification. One-half of the ASPAC region virtually lacked access to the most basic sanitation facilities (ADB 2006). Untreated sewage and garbage are intentionally and/or unintentionally drained into open drainage ditch, creek and stream, resulting in the pollution of a variety of fresh water reservoirs such as rivers, pond, lake and the likes.
Irrigated agriculture also becomes a pollution source. For instance, irrigated agriculture is the main source of nitrate pollution of ground water and surface water. Fertilizers and pesticides are polluting both water and the atmosphere, and nitrogen and phosphate enrichment causes eutrophication in various water bodies. Build-up of salts through irrigation affects as much as 20 percent of the total irrigated area (World Bank 2006).
Farmers in developing Asian countries could not help but use whatever water they could get, oftentimes using highly polluted water for irrigation, washing and processing of produce. When polluted water is repeatedly irrigated to crops, and/or used for harvest-washing, there is a great risk for the harvests to be seriously contaminated with various hazardous chemicals and virulent germs. In California, to cope with water scarcity and prevent pollution, about 46 percent of the total recycled water was used for agricultural irrigation in 2002. Redirecting nutrient-enriched wastewater from being discharged into drainage, streams, and lakes for other useful purposes is one of the promising solutions to prevent pollution and maximize resources (Water Facts 2004).
It is therefore a matter of urgency to examine the current status of agricultural water quality in the ASPAC region, and its relation to the safety of agricultural produce for human consumption. In addition, a prompt action should be taken to develop promising technologies and water management strategy for improved agricultural water quality and sustainable water resource management for the food safety of Asian consumers.