Thames Water has been hit with a record-breaking fine for polluting a canal.
The sentencing judge said the £1 million punishment underlined the need for "very large organisations" to "bring about the reforms and improvements for which they say they are striving", after the company repeatedly caused the Tring sewage treatment works to enter the Wendover Arm of the Grand Union Canal in Hertfordshire.
The charges relate to repeated discharges between July 2012 and April 2013.
The fine for Thames Water Utilities Limited is the highest for a water company in a prosecution brought by the Environment Agency (EA). Thames was also ordered to pay costs of £18,113.08 and a victim surcharge of £120.
The company pleaded guilty at Watford Magistrates' Court in May to two charges under the Environmental Permitting (England and Wales) Regulations 2010.
Sentencing at St Albans Crown Court today, Judge Andrew Bright QC said: "The time has now come for the courts to make clear that very large organisations (such as Thames Water) really must bring about the reforms and improvements for which they say they are striving because if they do not the sentences passed upon them for environmental offences will be sufficiently severe to have a significant impact on their finances."
The court heard that poorly performing inlet screens caused equipment at the works to block, leading to sewage debris and sewage sludge being discharged into the canal.
Routine samples of the discharge taken on January 31 2013 contained high levels of iron and aluminium, and showed a high chemical oxygen demand.
Emily Rowland, EA environment officer, said: "We welcome the court's decision to penalise Thames Water for serious breaches of its environmental permit, which led to pollution of the Grand Union Canal.
"We take these types of incidents very seriously and will do everything within our powers to safeguard the environment and people affected, and that includes holding to account those whose actions put the environment at risk."
The EA received complaints from members of the public and the Canal and Rivers Trust about pollution in the canal. Officers attended the site on several occasions, and saw sewage debris including sanitary products and ear buds in the vicinity of the outfall.
Thames Water explained to the court that it spent £30,000 on replacing the equipment at Tring.
It has taken steps to avoid further such incidents and there has been a significant improvement in its recent environmental performance, the EA said.