Utilities companies aren't very consistent here, eh? When we moved we had to give 10 days notice for DEH (electric) but Cosmote told us not to notify them until a day before otherwise we would find ourselves without a phone or the internet very quickly (& in fact on the day we moved in to our new property...the very next day.... a OTE engineer rang my mobile asking to come round and connect us...impressive!)...shame there were no lines available but that's another story.
The water company, (Δεμος) don't seem to care whether you pay them once a year or not.
I love the chaos here.