WATER pump failures resulted in increased levels of sodium hydroxide entering the water when thousands of Bolton customers were without water on two occasions in 2015.

On Tuesday United Utilities was fined a total of £200,000 for failing to deliver safe drinking water in 2015 between March 31 and April 3, and July 19 and 22.

The pump failures meant an increase in the amount of sodium hydroxide — caustic soda — being added to the water, increasing the pH level of the water above permitted limits.

In his sentencing remarks Judge Graeme Smith, said: "[This] meant that the final stage of the disinfection process was potentially less effective."

Sodium hydroxide is used in the water treatment process to regulate the pH of the water to make sure it is not too acidic or too alkaline.

In deciding how to fine the company Judge Smith took account of the company's financial history noting in the years 2015-17 United Utilities had had an annual turnover of 'approximately £1.7 billion'.

There were no sentencing guidelines for the judge to draw upon for these offences but Judge Smith heard legal precedents that said: "A fine needs to be large enough to bring that message home where the defendant is a company not only to those who manage it but also to its shareholders."

The judge was critical of United Utilities having failed to provide water twice for the same reason.

He said: "Each incident involved the combination of a number of factors which can only be described as a catalogue of errors."

Judge Smith also took account of a number of mitigating circumstances.

He noted the 'actions of the defendant were not deliberate' and that the company 'cooperated fully' with the Drinking Water Inspectorate and guilty pleas were entered at the first opportunity.

Judge Smith added that United Utilities 'paid voluntary compensation to those affected' exceeding £1.5 million and the company had now made 'significant' investment' into Sweetloves and other sites exceeding £150 million.

Judge Smith concluded saying: "The harm from the incidents was low; and the culpability was high."