We're not on mains water so it's pumped up from an aquifer and stored. My limited understanding is that tank has UV filters to get rid of the nasty bacteria and those filters had/have not been properly cleaned so coliform and enterococci (I think) were detected in last week's tests.

Further tests carried out by the council yesterday and we await results but don't necessarily trust what the management tells us so are going direct to the council as well. We have a right to know what's going on.