This article analyzes the publicness of early modern cities and the character of samurai residences as urban dwellers through the water supply and use of the Edo period in Japan. Firstly, in Edo, a megacity with a population of about one million, the Shogunate organized samurai residences (mainly those of feudal lords, Daimyo) into geographical organizations, and samurai residences paid for the repair of water facility and the water fee, just the same as the townspeople. Next, in Fukui (provincial castle town), samurai residence (Daimyo's vassal) organization for waterway didn't exist. The samurai residences were relieved of the burden of maintaining the waterways due to poverty. And, before the later Edo period, samurai vassals were not punished for violating the rules on water use, but they were eventually included in the punishment. The gap in feudal status between samurai and townspeople narrowed. It was a process of creating a modern urban society composed of equal dwellers. Although Edo and Fukui belonged to the same category as castle towns, the urban publicness and the position of samurai residences were different due to their dissimilar political positions as the Shogunate capital city and the Daimyo's provincial castle town.