This Practice Note explains the issues lawyers need to think about when advising a client following a waste offence, water offence, environmental permit offence, pollution or other environmental breach. It covers the need to prevent further environmental damage following an environmental incident, the duty to report the incident to environmental regulators such as the Environment Agency (EA) or local authority, the collection of evidence during the investigation, interaction with the investigating regulator including responding to EA investigations or other regulator investigations, and what to consider when conducting an internal investigation into an environmental breach such as the production of internal investigation reports into environmental offences.