SIEMENS

Some 71 percent of the earth’s surface is covered with water. However, only a little less than 3 percent of this is fresh water, and most of that is contained in glaciers and snow. Moreover, the fresh water that is freely available is also distributed very unequally. In fact, 60 percent of the world’s usable reserves of drinking water are located in only ten countries. According to the World Health Organization (WHO), some one billion people - two-thirds of them in Asia - still do not have access to clean drinking water. In Africa, 42 percent of the sub-Saharan population is forced to live with a water supply that is insufficient. China and India will also be facing serious water shortages by 2025. It will take investment of at least $10 billion per year to achieve the UN Millennium Development Goal of cutting in half the proportion of the global population with insufficient access to clean drinking water by 2015.

Around 80 percent of infectious diseases worldwide are caused by contaminated drinking water. WHO reports that 1.8 million people die each year due to diarrhea diseases; 90 percent of these people are children under the age of five, most of them in developing countries. In India alone, around 1,000 children die from such diseases every day. The causes here include sewage water containing human or animal fecal matter that seeps into groundwater or wells through rotting pipes. These days, a whole range of organisms are used as standard indicators worldwide to determine whether water is contaminated. Efforts to identify contaminated water focus on the intestinal bacteria Escherichia coli, or the identification of the total number of heterotrophic bacteria in water samples. The challenge with drinking water analysis is that it requires detecting a small number of organisms in a large volume of water. Traditional procedures, which are simple but also time-consuming, involve the cultivation of individual cells of E.coli and enterococcus bacteria, which are then allowed to grow into visible colonies. Their presence is then determined by counting the colonies that have developed. Methods that make use of molecular biological techniques already employed for medical diagnoses would speed up the process. These would have to be adapted for use with drinking water analyses, however. In the so-called PCR procedure, for example, short E.coli-specific sections of DNA are duplicated. A fluorescent dye that integrates itself into the DNA makes the synthesized DNA fragments visible. Drinking water can be purified through different procedures that can also be combined with one another. Conventional methods utilize activated carbon, chlorine, ozone, and membrane filter systems, among others. Another possibility is to kill germs with high-energy UV radiation.

According to UNESCO, Finland has the best-quality water in the world, and is followed here by Canada and New Zealand. The index used to determine this ranking takes into account various factors such as the amount and quality of fresh water (especially groundwater), sewage treatment effectiveness, and compliance with environmental laws. Indicators used in the calculations include “dissolved oxygen,” “suspended solids,” “phosphorous,” and “permeability.” According to the German Association of Energy and Water Industries, however, an objective ranking should also include heavy metals and nitrogen content.

The development of water treatment techniques has been shaped primarily by Germany, Austria, and the U.S., whereby their stringent regulations are also frequently adopted by other European countries. The European limit for nitrates, for example, is 50 mg/liter - but in the U.S. it’s only 10 mg/liter. Still, experts don’t always agree on the permitted concentrations for every substance. Whereas the EPA in the U.S. sets a limit of 30 micrograms (μg) per liter for uranium, the WHO recommends no more than 15 μg and Germany’s Federal Environment Agency recommends only 10 μg. Lead pipes are a problem as well, especially in buildings constructed before 1950. In areas with soft water, the use of such pipes can lead to high concentrations of lead. Regular ingestion of small amounts of lead by young children can damage the process of blood formation and the development of their nervous systems. The EU, for its part, plans to revise its drinking water directive by 2013, at which time the limit for lead will be lowered from the current 25 μg/liter to 10 μg/liter.