Geothermal heat pump systems used to tap into near-surface geothermal energy are either geothermal probes, geothermal collectors or heat pumps that use groundwater (extraction and absorption wells). Heat probes and collectors are heat pumps in a closed system in which a heat transfer fluid is passed through the ground and groundwater in the probe circuit without direct contact in order to absorb the heat stored in it. The heat transfer fluid is usually a slightly water-polluting substance of water hazard class 1.

The contractor must notify the lower water authority at least 6 weeks before commencing drilling or work that penetrates so deeply into the ground that it may have a direct or indirect effect on the movement or quality of the groundwater.

As part of the notification procedure, it is checked whether the project requires a permit, for example due to unfavorable hydrogeological conditions.

If the facility is to be used commercially, notification is also required in accordance with Section 40 of the Ordinance on Facilities for Handling Substances Hazardous to Water (AwSV).

Fees
The notification according to § 49 WHG i.V.m. § 41 ThürWG usually results in a chargeable decision with corresponding conditions. The fee varies depending on the course of the procedure and the type of geothermal energy use.