Great info there, MB!
In our case we're living in a rental with a typical landlord with a reluctance to do anything on the property that costs money. We are also rather grateful we have this rental (considering our circumstances) and will not be rocking the boat as finding another rental may be a bit difficult.
The water tank is probably about 12 years old (the same age as the house) and is leaking in several places. With the idea of checking inside, maybe even dropping in a chlorine tablet, I bought a stepladder and we tried to open the inspection hatch but it seems to be almost fused to the tank as if it has never been opened.
There are no water filters fitted.
Must admit that the water tastes great and we have not had any stomach aches; it was only after a little 'education' that we decided to drink only bottled water. We did enquire with the local health authority about testing our water but were told that unless there was a distinct metallic taste, a discolouration or frequent bouts of stomach problems they would not test the water.
When you think about it, a lot of debris and chemicals can be washed into and contaminate ALL water supplies wherever you live, and whilst some filtering and sterilisation takes place contaminants do get through and generally nobody's worse for it. (Though I do recall some accidental water quality problems in the UK, some serious, and a general worry about hormones from contraceptive pills escaping the filtering system in the UK.)
Mind you, I do wonder about the possibility of 12 years of sludge in our water tank ... Sick: