When I was in Rome, I got two warnings from the locals:
Beware pick pockets and keep your valuables safe and covered in the streets.
Don't buy water bottles from the guys on the street: they might be used bottles.
Pick-pocketing is obviously illegal no matter where you are, but what about the second one: Is it legal to sell water in used water bottles in Rome? Is it legal in the U.S.?
This would be illegal in the United States, and my guess (although I've not looked) it would also be in Rome, as well as any other first-world (for lack of a better term) nation. Bottling water in the US is heavily regulated by the FDA. You can read all about it at this link: http://www.fda.gov/Food/FoodborneIllnessContaminants/BuyStoreServeSafeFood/ucm077079.htm
For general purposes 21 CFR Part 129, states: These regulations require that bottled water be safe and that it be processed, bottled, held and transported under sanitary conditions. Processing practices addressed in the CGMP regulations include protection of the water source from contamination, sanitation at the bottling facility, quality control to assure the bacteriological and chemical safety of the water, and sampling and testing of source water and the final product for microbiological, chemical, and radiological contaminants. Bottlers are required to maintain source approval and testing records to show to government inspectors. Checking adherence to part 129 regulations is an important part of FDA inspections of bottled water plants.
Don't (ever, ndr) buy water bottles from the guys on the street
They do not have a license and a registered VAT number, so they are not permitted to sell anything. No tax, no work! That is the legal reason related to tax regulation.
they might be used bottles.
Please refer to @gracey209 answer
