Blue-coloured water from hot tap

[purplelily]

Hi, hope you can help.
My parents have a property in France, and blue-coloured (note: not green-blue) water has started coming from the hot taps.
My Dad thinks it's something to do with the immersion heater, but can anyone tell me how we might be able to deal with this?
Thanks in advance,
pl

[tickledtrout]

look at http://www.dwi.gov.uk/consumer/concerns/copper .shtms