These water fountains flow constantly with fresh drinking water for anyone to use and they are everywhere in Rome. Covering the spout with your finger forces the water out a hole on top, creating a arch of water at perfect πΌπ΅πΎπ»πΉπ²π·π° height. The Romans were/are with us.
You can fill your bottle from these. I'd mark them along my cycling routes and fill up.