This document sets out Ofwat’s final decision with respect to the imposition of a financial penalty on Southern Water. It includes updates and revisions following the publication, on 25 June 2019, of a notice of our proposal to impose a penalty on Southern Water. Taking account of the representations we received to that notice, we have, in particular, updated the Executive Summary, Section 1 (Imposition of a financial penalty) and Section 5 (Reasons for imposing a financial penalty and the level of that penalty) of this document. Section 6 (Summary of representations or objections) has been revised to outline the full extent of the representations that we received and to set out our response and final position on the issues raised. There is also now an Annex, which summarises some of the representations that we received and details our response to those representations.