While walking around a few different neighborhoods north of Shinagawa, I came across this interesting assembly. If you look closely around different areas in the Kanto region, you can usually find an old-fashioned hand-pump like this one, still supplying water for non-drinking purposes (usually used for cleaning).
I had always assumed that the groundwater in Tokyo was so highly contaminated with God knows what sorts of hazardous chemicals; actually I had wanted to go around with a few flasks, take some water samples and have them analyzed, just to see what sort of toxic brew I had found.
So, seeing the goldfish swimming in water here gave me pause. They didn’t appear to have cancerous growths on them, or swim in circles or provide any indication of neurological dysfunction. Might the groundwater not be as bad as I had thought? I wonder... (...but not enough to try it for myself!)