From 2nd October 2023, there are changes coming to the Environmental Permitting Regulations 1996 (under S.I 2023 No. 651 Environmental Protection The Environmental Permitting (England and Wales) (Amendment) (England) Regulations 2023) and heat will become a considered potential pollutant in groundwater.
Closed loop ground source heat pumps which are new systems on or after the 2nd October will be under General Binding Rules. These include binding rules such as not being within 250m of protected sites or ancient woodland, not within 50m of a well or spring or borehole supplying water used for domestic/food production. Also, all equipment used much comply with British Standards and Ground Source Heat Pump Association Standards and any decommissioning must not cause risk of pollution. The system must be fully sealed and must not mobilise contamination to cause pollution of surface water or groundwater. The threshold for releasing heat is not defined yet. Any divergence of the binding rules will have to apply for a bespoke permit.