Groundwater is all the water in the soil and substrate. This water comes from rainfall, or from the soil via ditches, lakes, streams and rivers. Groundwater is used for, among other things, drinking water, growing food, industry, nature and energy. The soil may consist of several unconnected layers which contain water. Not all groundwater is fresh water because, in coastal areas, you also have salty or brackish groundwater.
At some locations the soil is polluted. This also has consequences for the quality of the groundwater. If groundwater flows through contaminated soil, it can spread the contamination.
Source of drinking water
Groundwater is the most important source of tap water. 60% of Dutch tap water is made from groundwater. Beer brewers and manufacturers of soft drinks also use groundwater during their production processes. Drinking water companies and manufacturers take preventative measures, or use additional purification techniques to prevent contamination from the groundwater ending up in the drinking water or the products. Companies prefer to use groundwater from deeper layers for drinking water and other drinks because this water is extremely clean.
Agriculture, vegetable gardens and groundwater quality
Plants remove water from the soil. Good quality groundwater is therefore important for the cultivation of healthy agricultural crops and for vegetable gardens.
If the ground water is polluted, it might be possible to take measures depending on the depth of the groundwater and the type of crop. Possible measures include remediation, cultivating crops in plant troughs or ensuring sufficient amounts of fertiliser and lime.
The quality and quantity of groundwater is a responsibility of the provincial government
It is the task of the provincial governments to protect the quality of the groundwater, for example in water extraction areas, and elsewhere. Groundwater quality is an obligatory element of the provincial environmental ordinance.
Use of groundwater
A permit is required before groundwater can be extracted from the soil. In the case of small extractions (less than 150,000 m3/year) the water board is responsible for granting the permit. For large extractions, for example for drinking water extraction, industry and geothermal energy, the permits are granted by the provincial government.
The permits allow the government to control which and how much groundwater is used for the various functions. In this way sufficient high-quality groundwater remains available for drinking water and other uses.
Water Framework Directive
Groundwater is not limited by borders. The European Water Framework Directive stipulates that all the groundwater has to be of good condition by no later than 2027. This means that no contaminated substances are allowed to end up in the groundwater and that the quality of the groundwater must not deteriorate. Special targets apply to protected areas. According to the Water Framework Directive, the water is divided into 23 so-called groundwater bodies.
Checking the groundwater quality
The quality of the groundwater is monitored continuously. There is a national monitoring network with approximately 350 wells, maintained by RIVM and provincial monitoring networks. In these wells chemical substances, such as nitrate, pesticides and heavy metals, the amount of water and the salt content of the groundwater are measured. In addition to these generic tests there are also specific tests for nature reserves and drinking water extraction areas.
Drinking water in the Netherlands is always of good quality. You can quite happily drink the tap water. Do you want to start a vegetable garden? If so, check to see whether there is any information on contamination in the soil or the groundwater. If you have any doubts or questions, please contact your municipality.
If there is contamination, you can take measures to remove or limit the risks, for example:
- Cultivate vegetables in plant troughs with clean topsoil on top of a root-proof membrane;
- Do not allow children to play on contaminated ground;
- Use gloves;
- Ensure optimal fertilisers and lime so that the plants absorb fewer heavy metals;
- Always wash vegetables you have cultivated yourself thoroughly.