RIVM has developed the Groundwater Risk Assessment Toolbox. This risk assessment toolbox allows local authorities to quickly determine whether a specific groundwater application is safe. They can then take action if necessary. The risk assessment toolbox assesses the possible risks of hazardous chemicals in groundwater. It focusses on the impact on human health, on microorganisms in the groundwater, on drinking water extraction in the Netherlands and on surface water. This is the first time that such a broad assessment has become possible for groundwater.

The Risk Assessment Toolbox analyses the quality of groundwater

The quality of groundwater in the Netherlands is deteriorating. At the same time, we are using groundwater for different purposes. It is therefore important to be able to determine whether it can be used safely. 

In terms of health, the risk assessment toolbox analyses how and to what extent humans come into contact with hazardous chemicals from groundwater through various ‘pathways’. Some people use groundwater as drinking water, for example, or they eat vegetables that have absorbed hazardous chemicals from groundwater through their roots. Hazardous chemicals present in the groundwater may also evaporate and end up in the indoor environment.

The risk assessment toolbox supports decision-making 

The immediate reason for developing the Groundwater Risk Assessment Toolbox is the Environment Act, which will come into force on 1 January 2024. Under the Environment Act, it will no longer be mandatory to clean up contaminated soil. Instead, the province, water board or municipality responsible will determine whether and how to intervene. 

The Groundwater Risk Assessment Toolbox helps these decisions. Investigating groundwater quality at a specific location will make it clear where and what the problems are. This will allow the competent authorities to quickly determine what purposes groundwater can be used for at that location and whether measures (such as remediation of polluted groundwater or limiting its use for irrigation) are needed. 

The three steps in the risk assessment toolbox, mainly for experts

The risk assessment toolbox includes three tiers to examine whether groundwater contains a hazardous amount of chemicals. The first tier is to determine whether these chemicals exceed the corresponding limit value set for groundwater use. If so, the risk is investigated in more detail in the subsequent steps. These steps require more knowledge on how substances are transported in the subsoil and how they can be taken up by humans. In practice, this risk assessment toolbox will primarily be used by consultancy firms and environmental agencies. 

The Groundwater Risk Assessment Toolbox can be applied using a software package (decision support system), which is available online as a beta version (in Dutch only): https://www.risicotoolboxbodem.nl/grondwater.