Blue/ Green water marks on bath

[GreatGooglyMoogly]

I assume there is some kind of mineral in our water that makes it blue-ish, but it leaves marks where the taps have dripped. Can anything get rid of these?

Ajax or Barkeeper's Friend will remove these marks.

Brilliant, thanks Can you buy Barkeeper's Friend at the supermarket?

I've seen in in hardware shops but you can get Ajax in the supermarket.