An under fire water firm told customers to ‘add a slice of lemon’ to improve the taste of ‘mouldy’ water.

Now South West Water has been fined after it admitted supplying water which was unfit for human consumption.

The firm had told the 40,000 customers in the affected area to boil the water or ‘add a slice of lemon’ to improve the taste.

The Exeter based company admitted that between June and August 2018 at Bratton Fleming, near Okehampton, and Horedown, near Ilfracombe, they supplied the unfit water for users.

The two water treatment plants took water from the Wistlandpound Reservoir, where South West Water spent more than £1 million to improve its quality after the incident.

Plymouth magistrates court heard the water was ‘mouldy and musty’ and that a similar problem had occurred at the nearby Roadford Lake in West Devon three years before.

District Judge Miss Jo Matson said: ‘South West Water should have been prepared for such an event and reacted more quickly.’

She said a company the size of South West Water failed significantly in dealing with this incident, and also failed to supply alternative drinking water to affected customers.

Some customers complained that the water was ‘mouldy, earthy, disgusting, sewage’ and made them ‘gag and sick’ and it had a significant adverse effect on them although it did not affect human health.

The judge said the company has an average annual turnover of £572 million and an average annual profit of £141 million.

The court heard SWW, which has a one star rating in the Environment Agency’s four star rating system, admit:”It shouldn’t have happened and was genuinely sorry.”

The judge fined the firm £233,333 and ordered them to pay substantial costs too.

A SWW spokesperson said: ’We deeply apologise to our customers affected by this incident in 2018, which was caused by an algal bloom on the reservoir.

“We recognise that unpalatable water, even when safe to drink, is absolutely unacceptable, and this was reflected in our guilty plea at the earlier opportunity.

‘Since then, we have made a number of major investments of up to £1 million to the site to reduce the risks of such events occurring again.’

The company said the algal bloom was caused in part by an unusually dry and hot summer but the prosecution rejected that saying it was not the case it was the ‘weather’s fault’.

It said the water was safe to drink.

A spokesman for Defra, which has ultimate oversight over the industry, said they could not comment until after the period of mourning for Her Majesty Queen Elizabeth II had concluded.