Much of the Environment Agency of England & Wales's recent experience of the regulation of open-loop ground source heat pumps (GSHPs) has come from the increasing number of systems being installed into the confined Chalk of central London. Information collected through a Consent to Investigate a Groundwater Source demonstrates the likely well yields and the impact on other protected rights or water bodies, information that is then included in an abstraction licence application. As a result of the Environment Agency's local licensing policies in London and the net cooling requirements of developments, the majority of systems return heated water to the aquifer, thus requiring a Consent to Discharge. To gain this consent, applicants must provide enough information to assess the effects of re-injecting heated water into the confined Chalk. In the last 5 years, valuable lessons have been learnt as the Environment Agency has had to adapt existing regulatory processes to manage the environmental impacts of these systems. However, as GSHPs increase in number and proximity within London, applications become increasingly complicated for both the applicant and the Environment Agency. It is expected that the granting of future licences and consents will depend upon the quality and thoroughness of supporting assessments.