[3] In June 2019, Ofwat proposed a fine of £126 million as a result of Southern Water's failures to operate its wastewater treatment works properly and deliberately misreporting its performance.

This includes the company running guided tours of the Victorian sewers of Brighton and Hove and public access to Bewl Water, one of the largest reservoirs in England.

[21] In 2007, Ofwat announced its intention to fine Southern Water £20.3 million for 'deliberate misreporting' and failing to meet guaranteed standards of service to customers.

[22] Southern Water Chief Executive Les Dawson said: "Today's announcement draws a line under a shameful period in the company's history" and "we accept this fine - we have no arguments with it".

[23] Crawley Magistrates' Court heard that the Environment Agency received calls from members of the public after dead fish were seen in the Sunnyside Stream in East Grinstead on 30 August 2009.

Following an investigation, in June 2010 Southern Water was fined £3,000 after it admitted polluting 2 km of the Sussex stream with raw sewage, killing up to a hundred brown trout and devastating the fish population for the second time in five years.

[26] A leak of sewage from Southern Water's plant at Hurstpierpoint pumping station, West Sussex, lead to fines and costs of £7,200 in 2011.

[28] In November 2014 Southern Water were fined £500,000 and agreed to pay costs of £19,224 at Canterbury Crown Court after an Environment Agency investigation found that untreated sewage was discharged into the Swalecliffe Brook, polluting a 1.2 km stretch of the watercourse and killing local wildlife.

The Environment Agency said that the discharge along a considerable length of coastline, resulted in a risk to public health and negative impact in an area heavily reliant on the tourism industry.

[4] Following a lengthy investigation, Ofwat concluded that Southern Water deliberately misreported data about the performance of its wastewater treatment works.

The investigation concluded that Southern Water had failed: to have adequate systems of planning, governance and internal controls in place to manage its wastewater treatment works; to accurately report information about the performance of these works; and to properly carry out its statutory duties as a sewerage undertaker, to make provision for effectually dealing with and treating wastewater.

In response to Ofwat's findings, Southern Water announced that following its own internal review, which highlighted multiple failures between 2010 and 2017, it was 'profoundly sorry' and 'working very hard to understand past failings and implement the changes required' to ensure it meets the standards its customers deserve.