Protecting drinking water against geothermal risks

Still waters in deep grounds

The government inadequately protects drinking water aquifers against the risks of drilling for geothermal energy. In the Netherlands Court of Audit’s opinion, this is a matter of concern. The Court concludes from an audit that there is no coordination of activities underground, where drinking water extraction and geothermal energy production can come into conflict with each other.

What have we audited?

The audit is part of our multiyear Energy transition programme. The key question is: has the government effectively regulated and protected drinking water aquifers in light of the development of geothermal energy in recent years? We looked at the tension caused by the underground extraction of drinking water and the production of geothermal energy. These two national interests can be at odds with each other. The production of geothermal energy is accompanied by real risks: earth tremors, groundwater mixing and leakage of dangerous liquids. Geothermal production is overseen by the State Supervision of Mines. It has detected many instances of corrosion in geothermal pipes and in 2020 closed down three wells for a lengthy period in connection with potential leaks.

What are our recommendations?

We recommend that the Minister of Economic Affairs and Climate Policy and the Minister of Infrastructure and Water Management strengthen their coordination of the organisation and management of underground activities. Laws and regulations on underground activities must be made more coherent. The Drinking Water Act classifies the supply of drinking water as an ‘important interest’ but it is referred to as ‘equal’ to geothermal energy in the policy strategy on the use of underground space. We recommend that the ministers put proposals to parliament to define, lay down and clarify these terms in law and then apply them consistently.