Official

The water that comes out when you twist the tap. Where does the tap water in Chuo-ku come from?
In the Edo period, Kanda Josui and Tamagawajosui were used. The latter was derived from the Tama River Hamura dam.
At present, according to materials from the Tokyo Metropolitan Waterworks Bureau, Chuo-ku is located.
(1)Asaka, Misato, Misono, Kanamachi, Higashimura Mountains
(2)Asaka / Kanamachi / Misato System
It seems that tap water is being supplied.
All of the above place names are the names of water purification plants. "Asaka" and "Misono" are taken from Arakawa, "Misato" and "Kanamachi" are taken from the Edogawa, and "Higashimurayama" is taken from the Tama River and Arakawa.
The point here is Arakawa's water. In Arakawa, water taken from the Tone Oir of the Tone River is supplied through the Musashi Channel, which is taken again at Arakawa's Akiga Setori Water Weir and sent to the water purification plant. The Edogawa River is also connected to the Tone River upstream, so most of the tap water in Chuo-ku depends on the Tone River system and the Arakawa system. In Tone Oizumi, in addition to tap water, water for other purposes such as agricultural water is also taken. When I went to the site, I was overwhelmed by how the taken water flowed separately.
We receive the water of grace coming from the upper reaches of the river. Let's use precious water carefully!

An overview of water intake from Tone Oizumi, system diagram, role, etc. can be found on the website of the Japan Water Resources Agency.