The two companies both have poor pollution records this year, but it will not be certain which will take top spot in the Environment Agency's annual water polluters' league until January. The firms' latest prosecutions were as follows:
Appearing before Hastings magistrates on 28 November, Southern Water pleaded guilty to causing sewage to enter the English Channel, contrary to section 85(3) of the Water Resources Act 1991.
The court heard that the Agency received a call from the member of the public in August 2002 complaining of sewage in the sea at Cooden, near Bexhill. It was a fine day and there were bathers in the water oblivious to the pollution.
An Agency officer found that sewage was being discharged across the beach from a surface water sewer following a fault at the local sewage pumping station.
Southern Water said that both the main and back-up pumps had failed and sewage had backed up into the storm tanks. Telemetry systems designed to raise the alarm as the levels rose failed, and sewage overflowed into surface water drains.
Southern pleaded in mitigation that heavy loads of sewage and rainwater had overloaded the pumps. Company staff were at the scene within 30 minutes of receiving notification from the Agency. Southern was fined £3,700 and ordered to pay costs of £1,324.
The case was the company's ninth court appearance and tenth pollution offence in 2003. Its fines now total £73,200 for the year.
South West Water was fined £12,000 on 10 December after admitting discharging sub-standard sewage effluent from its Kenn and Kennford sewage works near Exeter.
Central Devon magistrates heard that samples taken by the Agency showed that the effluent consistently failed to meet the limits specified in the company's consent to discharge to the river Kenn.
Filter beds at the works were functioning poorly, and one effluent sample taken in April 2003 exceeded the consent limit by almost 15 times. The river downstream was also found to be suffering from low dissolved oxygen and high ammonia levels.
South West Water was fined £12,000 - its largest fine this year - and ordered to pay £780 in costs.
The company has ten offences and nine court appearances this year, according to ENDS' calculations. However, South West's fines total only £41,000 compared to Southern's £73,200.
The Agency received a complaint on 15 January that the brook was polluted. It was found to contain sewage fungus and to be blue in colour. The source of the pollution was traced to the company's Swiss Cottage pumping station.
The court heard that one of the station's two pumps had been removed for repair and an alarm warning of high sewage levels on 8 January had been ignored. The discharge continued for a week and repeated alarms were assumed to be a malfunction.
Severn Trent was fined £3,000 and ordered to pay the Agency's costs of £2,991. It was the company's second pollution prosecution this year.
A valve failure at the works in June allowed sludge back into the sewage treatment process and impaired the final effluent quality.
Despite requests from the company, the Agency refused to delay a routine effluent sampling visit. A sample taken the following day showed that ammonia levels in the discharge were about half those in raw sewage and above the consent's "upper tier" limit.
The Agency told the court that the works had previously had problems with ammonia levels. Despite claims that it was dealing with the problem, United had not fitted an ammonia sensor to the works outlet to warn of treatment problems.
United was fined £5,000 and ordered to pay prosecution costs of £1,646. It was the company's seventh pollution offence and sixth court appearance this year, bringing its total fines to £44,500.