The global water crisis also involves water pollution. For water to be useful fo
The global water crisis also involves water pollution. For water to be useful for drinking and irrigation, it must not be polluted beyond certain thresholds. According to the World Health Organization, in 2008, approximately 880 million people (or 13% of the world population) did not have access to safe drinking water. At the same time, about 2.6 billion people (or 40% of the world’s population) lived without improved sanitation, defined as having access to a public sewage system, septic tank, or even a simple pit latrine. Almost all of these deaths are in developing countries, and around 90% occur among children under the age of 5 (Figure 1). Compounding the water crisis is the issue of social justice; poor people more commonly lack clean water and sanitation than wealthy people in similar areas. Globally, improving water safety, sanitation, and hygiene could prevent up to 9% of all diseases and 6% of all deaths.
In addition to the global waterborne disease crisis, chemical pollution from agriculture, industry, cities, and mining threatens global water quality. Some chemical pollutants have serious and well-known health effects, whereas others have poorly known long-term health effects. In the U.S., more than 40,000 water bodies currently fit the “impaired ” definition set by the EPA, which means they could neither support a healthy ecosystem nor meet water quality standards. In Gallup public polls conducted over the past decade, Americans consistently put water pollution and water supply as the top environmental concerns over air pollution, deforestation, species extinction, and global warming.
Any natural water contains dissolved chemicals, some of which are important human nutrients, while others can harm human health. The concentration of a water pollutant is commonly given in very small units such as parts per million (ppm) or even parts per billion (ppb). An arsenic concentration of 1 ppm means 1 part of arsenic per million parts of water. This is equivalent to one drop of arsenic in 50 liters of water. To give you a different perspective on appreciating small concentration units, converting one ppm to length units is 1 cm (0.4 in) in 10 km (6 miles), and converting one ppm to time units is 30 seconds in a year. Total dissolved solids (TDS) represent the total amount of dissolved material in water. Average TDS values for rainwater, river water, and seawater are about four ppm, 120 ppm, and 35,000 ppm, respectively.
Water Pollution Overview
Water pollution is water contamination by an excess amount of a substance that can cause harm to human beings and/or the ecosystem. The level of water pollution depends on the abundance of the pollutant, the ecological impact of the pollutant, and the use of the water. Pollutants are derived from biological, chemical, or physical processes. Although natural processes such as volcanic eruptions or evaporation sometimes can cause water pollution, most pollution is derived from human, land-based activities