What is it?
Drinking water is extracted from rivers, streams and lakes (fresh surface water) and from below ground (groundwater). Groundwater is more pure than surface water, because it has been filtered by the soil. Nevertheless, before groundwater can be drunk, it usually needs to be treated at a treatment plant, where it passes through a (sand) filter and may undergo decalcification. Surface water contains a variety of pollutants from agriculture, industry and homes (e.g. pesticides and pharmaceutical residues). Consequently, surface water isn't fit for drinking until it has been thoroughly treated. This is carried out at treatment plants, where chemicals are removed by settlement and filtering or broken down by UV light. In some places, surface water is pre-treated by running it through sand dunes, which act as natural filters. The water then enters the groundwater table, from which it can be re-extracted.
The supply of groundwater and surface water is regarded as an ecosystem service. In the Netherlands, such water is normally consumed in the form of tap water or bottled water (well water).
In order to produce sufficient drinking water, it is important that enough rainwater is able to filter into the soil to keep the groundwater table topped up. Fresh surface water is held in reservoirs (e.g. the IJsselmeer and the Biesbosch), so that a sufficient reserve is available. If too much groundwater is extracted for drinking, natural habitats can dry out, potentially leading to water shortages for agriculture or manufacturing.
The amounts of pollution in surface water need to be kept as small as possible, in order to keep the cost of water treatment down. In addition, sufficient fresh water has to be retained in low-lying parts of the Netherlands to prevent salinization (rising salt concentration).
The quality of our drinking water is threatened by fertilisers (nitrate, phosphate), heavy metals, pesticides and pharmaceutical residues. As well as influencing drinking water quality, such substances have an adverse effect on the biodiversity in surface waters.
In real life
In the Netherlands, various areas are designated as drinking water extraction areas. Most are natural habitats (the Veluwe, dune lands), where the quality of the fresh water is protected by regulations and specially adapted management methods. In addition, we have both natural and artificial reservoirs for the retention of surface water for use in times of drought or poor (river) water quality.
In urban areas, groundwater levels can be supported in various ways. One is to reduce the amount of land that is paved over, e.g. by creating more green spaces. Other options include preventing rainwater from running straight into the sewers and creating WADIs (systems that allow water to drain away by infiltration).
In rural areas, intelligent combinations of water storage and water extraction on agricultural land and natural habitats can contribute to a sustainable water supply (e.g. in the Oostpolder).
No practical examples are currently available.
- Drinking water quality
- Average shortage of water for drinking and industrial purposes in a year (soon available)
- Drinking water extraction from groundwater
- Availability of freshwater, salinization
- Drinking water extraction sites from surface water
- Salinization of surface water
- Groundwater protection areas