A water tank infected with Cryptosporidium has been drained and will be cleaned on Saturday, South West Water said.
Around 16,000 households in the Brixham area of Devon were told to boil drinking water after 46 confirmed cases of the disease.
Cryptosporidiosis it is caused by a small parasite and can cause vomiting, stomach cramps and watery diarrhea that lasts about two weeks.
More cases are expected to be confirmed due to the delay in the development of symptoms – and about A further 100 people around Brixham reported signs of this on Friday.
Rita Bristow said she knew of only four of the 21 homes in Raddicombe Close, on the outskirts of Brixham, that had not had at least one person sick with cryptosporidiosis.
South West Water believes the parasite likely entered the supply through a damaged pipe in a field containing animal faeces.
A contaminated water tank at Hillhead Reservoir, where Cryptosporidium was detected, was drained overnight and will be “thoroughly cleaned” on Saturday before refilling begins, South West Water said.
However, it remains unclear when supplies will be safe again, as the company emphasized that it would “only lift boil water advisories when it is absolutely safe to do so.”
The local deputy warned that “heads will roll” over the incident.
Conservative MP Anthony Mangnall, whose constituency includes Brixham, told LBC: “This is such a serious matter that yes, I think heads are going to roll over this.”
He claimed that the vendor took too long to issue its security alert.
16,000 businesses and residents are affected by the boil water advisory. Photo: Água Sudoeste
Mr Mangnall said: “From starting this week with a denial from South West Water that it had anything to do with them, delaying the fact that the boil water warning arrived – meaning thousands of people used the water network – to then issue it on Wednesday, and there are a lot of people who are very sick.”
He called it an “absolutely disastrous week” and said local residents were furious.
South West Water said it is “deeply sorry” and has been “working tirelessly” to identify the source of the problem and resolve it.

Bottled water stations have been installed in the area.
See more information:
What we know about the parasite found in drinking water
Parasite outbreak ‘destroyed’ businesses
Liberal Democrat leader Sir Ed Davey accused the government of not doing enough to hold water companies to account.
He told Sky News that companies were “profiting from the environment and public health” after several cases of sewage being released into rivers and seas.
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“Us [Liberal Democrats] I wouldn’t wait for pollution fines,” said Sir Ed.
“There should be a sewer tax on the profits of these water companies so we can get the money now.
“Much stricter regulation is needed… and the entire water industry may need to be restructured.”
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1:07
Kelly Holmes joins anti-sewer protest
It turns out that dozens of protests over sewage releases were planned for Saturday.
Surfers Against Sewage is hosting “paddling” demonstrations at 30 locations, with Olympian Dame Kelly Holmes among those taking part in the event in Brighton.
This story originally appeared on News.sky.com read the full story