Water is water is water – but there are different types of water and waters
About 72 percent of the earth's surface is covered with water
, 97 percent of which is seawater. Seawater shows great local differences, for example in terms of salinity. In the area of river mouths, brackish water, i.e. a mixture of salt and fresh water, has its own unique conditions.
Only three percent of the global water resources are fresh water. Of these three percent, around 69.5 percent are bound in polar ice, glaciers or snow covers and are, therefore, not accessible as drinking resources for humans. 30.1 percent of fresh water is groundwater and 0.4 percent surface water.
Groundwater is part of the water cycle and the water below the earth's surface
that is created by seeping water from rain, lakes or rivers. Groundwater resources are the most important source of the water supply in many regions of the world.
Around 74 percent of
drinking water in Germany comes from groundwater. The increasing pollution of the groundwater by agriculture and industry endangers and impairs the quality of the groundwater. Groundwater protection is subject to various legal regulations (e.g.
European Water Framework Directive) and related efforts.
Surface water is the water on the earth’s surface in rivers, streams, lakes, or reservoirs.
These are fed by rain and water from the earth's interior. Surface waters are the habitat of many animals and plants. In terms of infrastructure, rivers are also an important economic component: Sewage treatment plants discharge the treated wastewater via rivers, goods are transported via rivers and drinking water is obtained from them. Surface waters are polluted through contamination from, among other things, industry and agriculture. In order to use it as drinking or process water, it must be pre-treated.
Together with oxygen, drinking water is the basis of all human life.
Not only is it food, it is also important for cooking, personal hygiene and clean housing.
Drinking water can come from groundwater, surface water, precipitation or seawater. In Germany, around two thirds of tap water are obtained from groundwater, one third from surface water. We can drink it either untreated or after processing (i.e. cleaned, disinfected and, if necessary, changed in composition), if it meets the minimum legal requirements. The quality of drinking water is regulated in many national laws, guidelines, and recommendations.
In addition to tap water, other types of water also play a role as food and represent an own economic sector: spring water, medicinal water, table water and mineral water. For them, too, it is regulated by law which criteria each water must meet.
Water is also an essential component in many industrial production processes
.
It is required to operate plants or manufacture products. Depending on the use of various complex cleaning and treatment processes, so-called process water has different qualities and characteristics. It is used in medicine, pharmacy, chemistry, or biology. Process water is used to manufacture medicines, as solvents and cleaning agents or as battery and ironing water.
Process water includes the water types: demineralized, deionized, distilled and ultrapure water.
Industrial water is the least purified water and used in commercial, technical, agricultural and domestic areas. It is not suitable for human consumption but geared towards the requirements of the area of application. For example, toilets and irrigation or cleaning systems are increasingly operated with industrial water, not drinking water.
Wastewater is all the water that has been used in households, agriculture, industry and thus has been polluted to a greater or lesser extent.
Pollutants that get into the sewage system from households include dust and dirt particles, feces, leftover food, and detergents.
Pesticides and fertilizers used in agriculture end up in wastewater. As do heavy metals, plastics, pharmaceuticals and other micropollutants via industrial production and inadequate or non-existent disposal and recycling structures.
The task of
wastewater treatment plants is to purify the wastewater in a way that it can be fed back into the surface waters without disturbing the biological balance.