A report on ‘State of The Environment and Policy Retrospective: 1972–2002’ by United Nations Environment Programme (UNEP), states that the total volume of water on Earth is about 1400 million km3 of which only 2.5 per cent, or about 35 million km3, is freshwater. Of this only a fraction, approximately less than 1 per cent is accessible groundwater or surface water available for drinking. Most freshwater occurs in the form of permanent ice or snow, locked up in Antarctica and Greenland, or in deep groundwater aquifers. The principal sources of water for human use are lakes, rivers, soil moisture and relatively shallow groundwater basins. The Asia and the Pacific Region account for about 36 per cent of global run-off. Even so, water scarcity and pollution are key issues and the region has the lowest per capita availability of freshwater: renewable water resources amounting to about 3690 m3 per capita/year in mid-1999 for the 30 largest countries in the region for which records are available. In absolute terms, China, India and Indonesia have the largest water resources, more than one-half of the region’s total. Several countries, including Bangladesh, India, Pakistan and the Republic of Korea, already suffer from water scarcity or water stress. More will do so as population and consumption increases. For many of the world’s poorer populations, one of environmental threats to health remains the continued use of untreated water. However, the percentage of people served with improved water supplies increased from 79 per cent (4.1 billion) in 1990 to 82 per cent (4.9 billion) in 2000. About 2 billion people, approximately one-third of the world’s population, depend on groundwater supplies, withdrawing about 20 per cent of global water (600-700 km3) annually—much of it from shallow aquifers. Parts of India, China, West Asia, the former Soviet Union, the western United States and the Arabian Peninsula are experiencing declining water tables, limiting the amount that can be used and raising the costs of pumping to farmers (UNEP 1999). Over pumping of groundwater can lead to salt-water intrusion in coastal areas. In Chennai, India, for example, saltwater intrusion has moved 10 km inland, contaminating wells. Groundwater in districts of West Bengal, India, and in some villages in Bangladesh, for example, is contaminated with arsenic at levels as much as 70 times higher than the national drinking water standard of 0.05 mg/litre. The 2008 OECD Environmental Outlook to 2030 Report states that already 63 per cent of the population in Brazil, Russia, India and China together are living under medium to severe water stress; this share will increase to 80 per cent by 2030 unless new measures to better manage water resources are introduced. Another study by Food and Agriculture Organization (FAO) 2012 reported by UN Water: Statistics, Graphs and Maps, states that by 2025, 1800 million people will be living in countries or regions with absolute water scarcity, and two-thirds of the world population could be under stress conditions.
The 2012 United Nations World Water Development Report goes on to highlight that up to 90 per cent of wastewater in developing countries flows untreated into rivers, lakes and highly productive coastal zones, threatening health, food security and access to safe drinking and bathing water. Many industries—some of them known to be heavily polluting (such as leather and chemicals) are moving from high-income countries to emerging market economies and water pollution is on the rise globally. Everyday 2 million tonnes of human waste is disposed off in water courses world over while in developing countries, 70 per cent of industrial waste is dumped untreated into waters (UN Water-Statistics, Graphs and Maps).
Water quality is determined from the measurement of certain water quality variables such as faecal coliforms; biological oxygen demand (BOD); nitrates and phosphorus; suspended matter; heavy metals; organic metals; organic micro pollutants and more. A wide range of human and natural processes affect the biological, chemical, and physical characteristics of water, and thus impact water quality. Contamination by pathogenic organisms, trace metals, and human-produced and toxic chemicals; the introduction of non-native species; and changes in the acidity, temperature, and salinity of water can all harm aquatic ecosystems and make water unsuitable for human use. Numerous human activities impact water quality, including agriculture, industry, mining, disposal of human waste, population growth, urbanisation, and climate change. Nutrient enrichment has become one of the planet’s most widespread water quality problems. A report on ‘Clearing the Water’ by UNEP 2010 states that industrial activity releases about 300-400 million tonnes of heavy metals, solvents, toxic sludge, and other waste into the world’s waters each year. Mining and drilling create large quantities of waste materials and byproducts and large-scale waste-disposal challenges. Also widespread lack of adequate disposal of human waste leads to contamination of water—worldwide 2.5 billion people live without improved sanitation (UNICEF and WHO 2008). However, the United Nations Global Environment Monitoring System (GEMS) Water Programme is working to providing environmental water quality data and information of the highest integrity, accessibility and interoperability. These data are used in water assessments and capacity building initiatives around the world. GEMStat is designed to share surface and ground water quality data sets collected from the GEMS/Water Global Network, including more than 3,800 stations with close to 4.6 million records studied over 100 parameters.
The impairment of water quality is usually manifested when certain water sources cannot be used as safe drinking water, which is a direct contributor to water scarcity. The effective management of fresh water resources demands that attention be paid to water resource planning at local, regional and national levels and regulatory activities, including effluent control and enforcement. The threat of freshwater pollution is serious enough for many countries to have taken steps to control sources of contamination, which include regulating sewage disposal; constructing city sewage schemes; installing waste water treatment plants; treating and recycling industrial effluents; substituting harmful consumer products (such as phosphate in washing power); banning dangerous pesticides and industrial chemicals; water resources management; judicious utilisation of water; adoption of polluter pays concept; enhancement of traditional water harvesting systems; recycling of water and more.