We read and heard very different stories on water here in Italy from being very expensive, short supply to being cheap and plentiful. Is measured and costed per cubic metre (m3) by our supplier ACA, same region as Levi. Perhaps Levi can provide the cost per m3 for Reti if it is indeed costed the same, which I assume it will be. ACA have 3 bands; up to 100 m3 roughly = €0.48; 101-200 m3 = €0.68 and above €1.175, so quite a variation. We have used anything from 140 m3 to 161 m3 in the 3 years we have been here and it roughly cost just under €100 per year. Compared to the UK, that's very cheap, but a very good point by Relaxed is if main sewerage comes into the picture! We don't have this, so did not realise the potential cost, if anything like the UK, then this could really impact you bills. However I still think the cost will be a lot less than the UK. Of course all of this depends on your personal usage. All the above are "rough" as they do not include standing charges and because bills are sporadic and we've not had one this year at all...
One last point, keep an eye to your meter and the number of units uesd, in particular if it is whizzing around and you think you have no water being used... Many of the problems with high bills turned out to be leaks here and there, friend of our who did not have easy access to their meter, had a bill that ran into 1000's..