Experts say coliform is the bacteria that were found in drinking water supplies serving areas of upper Wensleydale.
Around 1,000 properties have been told to boil their drinking water after bacteria were found in the supply.
Yorkshire Water yesterday implemented a ‘boil order’ for homes and businesses in Hawes, Gayle, Appersett and Askrigg (DL8-3 postcodes) as a precaution.
Staff from the water firm have been in Wensleydale today to deliver leaflets about the issue to homes and businesses.
A Yorkshire Water spokesperson said in an updated issued today: “We regularly check our drinking water to make sure it meets our high standards and during our routine tests we have found bacteria in a small number of samples.
“Whilst our treatment processes take out any impurities in the water to make sure it’s of the highest quality, the coliform bacteria we have found in these samples is higher than we would normally see so as a precaution we are asking that customers boil their water before use until further notice.
“Our water quality team will continue to take samples to monitor the quality of the water in the area whilst we work hard to resolve the issues.
“We are working closely with the relevant health authorities (UKHSA – UK Health security agency) and taking the necessary precautions which in this case is to boil water before use. Boiling water will provide sufficient protection from any bacteria we have found.”