Drinking tap water

[cyborg]

My mum is looking for a water softner for her house abroad and it got me thinking about tap water. Why is it in some countrys we are warned not to drink from the tap, like spain? Surely they could have updated their water purifying plants or whatever by now?

Another thing i was wondering, is tap water safe to drink everywhere in the UK?

 

[cyborg]

Does drinking 'hard' water become bad for you? Looking at a kettle thats been boiling hardwater, and the limescale it collects it certainly doesn't look like it!