Talking about water quality in Spain is like discussing pieces of string as in “how long is a piece of string?”.
In our village water comes from a borehole and is filtered and purified by an automated plant. Sometimes after heavy rain the plant fails and we get the borehole water straight from the well - more like weird tasting weak tea than clear, clean water.
Since silver was mined locally until recently (C?cres area) there are the expected traces of various heavy metals in the deep groundwater along with clayey particulate matter.
It has a metallic odour which reminds me of colliery waste water pumped from mine workings in the area wher I was brought up in the East Midlands (North of Nottingham).
The local clerk at the Ayuntamiento says that the water presents no biological threat and is adequately chlorinated.
Most of the locals buy mineral water for drinking - 8 litres for about 1?00. I don’t drink the tap water copiously but will use it to clean my teeth or to wash down an aspirin etc.
Best wishes
Dave J