As I said, most Italians don’t drink tap water at home, because in many cities it has a funny taste (I guess due to the water treatment). If they don’t buy it at the grocery store (where it’s very cheap, even less than €.25 for a 2 liter bottle), they fill their own bottles at natural springs (when suitable) or at special dispensing outlets, installed by municipal water districts everywhere. These dispensing outlets dispense water that is treated with special methods that make water better than the tap water coming through the lead pipes to people’s homes. In this case, people reuse their bottles, therefore there is less environmental impact. The water is provided by water districts for free, therefore it’s even cheaper than the store.
Since Italians have this cultural practice of preferring to drink water other than the tap water coming in the home through the pipes, restaurants do not serve tap water, although some have started to serve specially treated water from the above mentioned dispensers using reusable bottles (for environmental reasons)
Some of you may not conceive or even object to the practice of not drinking tap water, for whatever reason (plastic waste or whatever) but it is what it is. Italians also can’t conceive the American cultural practice of not using a bidet after using the restroom, but also in that case, it is what it is. Every country has its own cultural idiosyncrasies.
Regarding the restaurants in Italy, there is also the fact that bottled water is extra revenue for them. Bottled water is, as I said, very cheap in Italy (€0.15/lt), but since it’s sold at at least €2 a bottle in a restaurant, that is a nice mark up. That is why if you ask a restaurant for tap water, some may find the excuse that is not safe for drinking, which is a lie.
But I don’t understand all the fuss here. Restaurants in the US apply at least a 500% mark up on wine while they charge at least $25 for corkage fee. In Italy restaurants only double or at most triple the price of wine, while the corkage fee (diritto di tappo) ranges from €5 to €10 max. Why, considering the extortionate practices of American restaurants, there is such a huge problem with paying €2 or 3 for a bottle of mineral water? I know it’s not the concern with plastic waste, since in the US we generate twice the amount of plastic waste per person as Italy (105kg per person in the US vs 56kg per person in Italy, according to the World Bank). Just get with the program and order bottled water. You’ll still save money over eating out in the US. You can drink all the tap water you wish when you return home or even when you are in the hotel in Italy (You can use the hotel bathroom sink tap or even the bidet, if you like).