A JUDGE said it was no wonder comedian David Walliams became ill after his 140-mile charity swim, as Thames Water faced its biggest fine ever for dumping raw sewage into the River Thames.

Hundreds of fish and birds died over a two-year period when 'out of control' treatment centres owned by the supplier sent untreated water into rivers in Oxfordshire and Buckinghamshire, a court heard yesterday.

Thames Water could now face a fine of more than a million pounds after tampons, condoms and sanitary towels were dumped into the famous waterway in Oxfordshire, with a litany of unaddressed problems branded 'a failure waiting to happen'.

Oxford City Council leader Bob Price has branded the company a 'disgrace', with affected sites including a pumping station in Oxford and treatment plants in Didcot and Henley which contributed to the Thames, Wye and Thame rivers being polluted between 2013 and 2014.

Thames Water admitted several charges of unlawful discharge and breaching ammonia levels under the Environmental Permitting Regulations. It will be sentenced on February 22 and could be ordered to pay compensation to people who were affected.

Speaking yesterday in Aylesbury Crown Court, Judge Francis Sheridan told the company: "This is likely to be the biggest fine Thames Water has ever faced."

He also alluded to Mr Walliams' mammoth swim of the Thames and said it was no wonder he was taken sick.

Walliams, who raised £1.1 million for charity, suffered from 'Thames Tummy' after completing the challenge.

The warning to Thames Water yesterday was welcomed by city council leader Mr Price, who added: "There was a big sense of public outrage that something like this could happen in the 21st century and this is a fully-justified decision by the court.

"There is nothing people value more than access to clean water and a clean environment.

"And given the rates people now have to pay Thames Water, it's a disgrace they couldn't preserve the basic tenets of good management at these sites.

"I hope it's a lesson to the company that will lead to improvements in its customer performance and a greater willingness to take into account the importance of looking after our local environment."

Prosecuting Thames Water on behalf of the Environment Agency (EA), barrister Sailesh Mehta outlined how a small site at Littlemore, Oxford, was at the centre of an investigation after a valve was left open and sewage discharged into the Thames.

Thousands of litres of sewage water were smelled by commuters in April 2013 when the error led to pollution after a pump failure.

Mr Mehta also described how scum was found floating on lagoons in Aylesbury while in Didcot, in April 2013, a cyclist reported seeing river water ridden with tampons, sanitary towels and nappies.

At Henley, Mr Methta said levels of ammonia in the river were 'devastating to life'. In July 2013 at least 50 dead fish were spotted.

The barrister told the court: "An [EA] officer attended and let effluent out and could smell sewage and could see brown scum."

The site at Henley was 'under-using' the capacity of its works and was dealing with 67 litres per second rather than the figure of 85 litres per second it should have been able to handle.

Mr Mehta also said a priority alarm, which should be responded to immediately, was tended to almost six hours later. Another alarm, which should have been dealt with within two hours, took 37 hours to be responded to.

A list of 'do's and don'ts' for staff published internally at Thames Water's Little Marlow site in Buckinghamshire, read to the court by Mr Mehta said: "Don't discuss your views on the cause of the problems with any customer, the Environment Agency or the press.

"Don't give any agreement that Thames Water will provide any information, statement or any interview to the Environment Agency."

Judge Sheridan branded the list a 'deplorable document'.

But after hearing of the amount of sanitary towels, condoms and nappies found in incoming sewage to the plant, he also suggested people should not treat toilets as a 'dump'.

He added: "It's not all down to Thames Water. There's a responsibility for everyone to use sewage system properly."

A Thames Water spokesman said yesterday: "We will issue a full statement at the appropriate time, after sentencing."

The company was fined £380,000 by Judge Sheridan in March 2016 following a similar example of pollution in Princes Risborough, Buckinghamshire.

It was also fined £1m two months previously for pollution at the Grand Union Canal in Hertfordshire.