Drilling noise coming from immersion heater

Pingu1

My immersion heater has started making a loud vibrating noise whenever I use the bathroom. It started today and I have no idea what the problem is. It made it when I flushed the toilet and turned on the cold water tap. It sounds like someone is drilling. Can anyone help please?

Davesnave

There is no connection between an immersion heater and a toilet, so what you are hearing is 'water hammer.'

A diagnosis of cause at a distance is difficult, hence:

http://www.practicaldiy.com/plumbing/pipe-noises/water-hammer.php