A fellow who works at a restaurant just finished tossing waste water onto the street in front of the establishment.
One thing you can't miss while living in Japan is people "watering" the sidewalks, pavement, and concrete in front of their homes and business establishments. In Japanese, this custom is called "uchimizu". Most often, this can be seen in the summer time and I have been told on several occasions that this is done to "cool off" the surrounding area. Personally, I have my doubts that occasionally spraying or ladling a bit of water on the steaming hot pavement in Tokyo in when the temperature is in the mid 80's and we have 80% humidity does much of anything to "cool" the area, but I'm no expert on such matters.
The other reasons given for this is that the glistening pavement looks nice and clean and keeping it wet keeps dust down. Presumably, that means the pavement pounding of passing pedestrians (say that 3 times really fast) isn't going to kick up dust that clings to the front of buildings. Mind you, you wouldn't conclude this from looking at the front of most buildings. Most of them have a fair bit of sooty-looking build-up from years of exposure to Tokyo pollution.
Somewhat surprisingly, there have been campaigns to promote uchimizu and it is considered the act of a good citizen. The reason I find it a little unusual that this would be something which is actively promoted is that this wastes water. However, it should be noted that the campaign does try to encourage people to use water collected from rainfall or from bathwater that is no longer useful rather than to turn their hoses out on the streets. On occasion, I have noticed people collecting water in basins from their downspouts and I believe they are doing so in preparation for a little uchimizu. It's quite noticeable when you see it because old plastic buckets, basins, or other liquid catching receptacles are frankly not that tidy or attractive-looking and seeing them in front of people's homes or businesses is atypical in largely tidy Tokyo. Now, I know why they are there and I have to applaud the folks who make this effort, even if I personally am not convinced (nor unconvinced for that matter) of the merits of it all.
Unfortunately, I most often see people in my area doing their uchimizu in one of two ways. They either do as the fellow above has done and toss out cleaning waste water (this picture was taken in the winter so it's clearly not about "cooling" the area) or they spray it down with a hose (or both). The campaign also encourages folks not to trouble others while they do this but all too often I see people only reluctantly turning their hoses away as pedestrians and bicycles approach. I guess that the busy sidewalks and streets make wetting the pavement too time-consuming if you have to pause for every passerby.
The main idea behind the uchimizu custom seems to be two-fold. One is that the act of ladling the water can be contemplative or meditative. I believe this is something which mainly applies to people who perform it as part of their usual habits at temples or monasteries. Somehow, I doubt the people quickly flicking pans of water onto the street out front are being very thoughtful in the 5 second it takes to empty them. The second part is that one is supposed to feel the "coolness" of the water by being in proximity to it or handling to it. This is probably part of a Japanese sensibility that doesn't translate well to western thinking and part of what forms their cultural connection with nature in ways to which we cannot relate as those notions are related to shared cultural mindsets.