Water chiefs say they have “identified and isolated” the source of the cryptosporidium contamination which has been affecting large parts of Lancashire for the past two weeks.
But United Utilities are continuing to warn consumers in Preston, South Ribble, Chorley, the Fylde Coast and parts of Blackburn to carry on boiling water until all traces of the bug have been eliminated from the network.
As the crisis entered its 14th day the company which provides water for the whole of the North West said it was still working hard to flush the system through before it could announce an all-clear.
A spokesman told customers on its Twitter feed on Wednesday morning: “We have identified and isolated what we believe to be the source.
“But it wouldn’t be appropriate for us to comment further as this will be subject to formal investigations.”
It was revealed on Monday that the probe into the contamination, which is believed to centre on the Franklaw Water Treatment Plant near Garstang, is being treated as a “criminal investigation.”
The Drinking Water Inspectorate is carrying out a detailed inquiry, but this does not involve the police.
The alert, which followed the region’s first positive tests for cryptosporidium in drinking water for at least 15 years, was introduced on Thursday August 6.
United Utilities has pledged to compensate all householders and businesses once the water supply is back to normal.