(Bloomberg) -- South West Water Ltd. is set to pay customers around £1.8 million ($2.3 million) in compensation after a parasite got into the local water supply, causing hundreds of people to become ill.

Around 16,000 homes and businesses the utility serves in England’s Devon county have been told to boil their water before drinking it, according to a government statement Friday. The utility, part of Pennon Group Plc, said Thursday it will raise rebates to affected customers to £115, from £15. 

The UK’s Health Security Agency confirmed earlier this week that it is investigating cases of the parasite, known as cryptosporidium, in the area around the coastal town of Brixham. The parasite causes diarrhea in humans that can last for two weeks or more. Most people recover, but it can be fatal among people with severely weakened immune systems.

On Friday, UKHSA said it has confirmed 46 cases of cryptosporidiosis, and 100 people have reported similar symptoms. However, the actual number is likely to be much higher because the agency told people not to contact medical services to report cases unless they need urgent clinical care. 

Like most of the UK’s water companies, South West Water is already facing public anger over illegal sewage spills and chronic leaks caused by decades of under investment in aging infrastructure. The utility is seeking permission to raise customer bills by 22% by 2030 to fund billions of pounds in upgrades to its networks, with a draft decision from the regulator expected on June 12.

On Thursday evening, Chief Executive Officer Susan Davy issued an apology to customers for the “disruption and wider anxiety” that has been caused. “While incidents like these are thankfully very rare, our customers expect a safe, clean, and reliable source of drinking water. I know on this occasion we have fallen significantly short of what you expect of us,” she wrote.

Local MP Anthony Mangnall criticized company’s response to the outbreak. “They have been slow to act and communication with customers has been very poor,” he said in a statement. 

Laura Flowerdew, SWW’s chief customer officer, on Thursday said the firm had identified a damaged valve on its network and that the fault may have caused the parasite to escape into the water supply. 

(Updates with number of cases in the first paragraph.)

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