Hi, We are experiencing freezing of Potable Water pipelines at site. These lines have not been insulated in the past as it was believed that insulated drinking water lines may encourage microbes in the water. This is an unknown area to me and I would be grateful if somebody could provide any guidance on the following: Is it likely that insulated potable water lines can encourage the development of microbes, and if so, what types of microbes? Thanks.

Lagging of water pipes is not going to raise temperatures to the extent you'll have to worry about legionella proliferation. Legionella Approved Code of Practice (COSHH) L8 is concerned with ensuring cold water systems are maintained below 20 degrees celcius. Whilst the bacteria can survive down to 6 degrees, it is the proliferation temperatures (>20) that are the big risk.

From 10 years experience of testing potable water quality within the water industry I can tell you lagging pipes will not cause a build up of bacteria. Our sites were tested daily or weekly and most pipes feeding the test taps were lagged due to lack of heating. While you are lagging the pipes make sure you havent got any unused pipes that have been capped off, these are what tend to cause problems as well as the usual culprit of header tanks feeding drinking water supplies! D.