United Utilities has advised customers in certain areas to boil their water before consuming it after routine tests at Franklaw water treatment works in Preston detected small traces of microscopic bug cryptosporidium in the water.
The firm contacted households in Blackpool, Chorley, Fylde, Preston, South Ribble and Wyre with the advice, which it said was a precuation but should be followed until further notice.
The company said it was putting cards through letterboxes of affected homes from today, as a supplement to efforts to communicate the advice via social media, newspapers, radio and TV.
Samples of water from the treatment works and the wider network showed that the traces of cryptosporidium were reducing. However, it said that testing would continue and the boiled water notice would not be lifted until United Utilities was “absolutely satisfied” that the water was back to normal.
United Utilities chief scientific officer Martin Padley said: “We’d like to thank customers for their immense patience as we work to restore normal service.
“As a precaution, we’d ask people to continue to boil their water for drinking, food preparation and brushing of teeth until further notice.
“The boiled water notice will apply throughout the weekend and, most likely, into the early part of next week. We’ll continue to keep customers informed.”
A notice on United Utilities’ website advised that people affected could continue to use tap water without boiling for general domestic purposes such as bathing, flushing toilets or washing clothes.
Investigations are ongoing into how the bug found its way into water at the treatment works.
Cryptosporidium can cause gastrointestinal illness – the main symptoms being diarrhoea and abdominal cramps.