Have you noticed all those trucks watering the streets? Im not referring to those watering plants on the sides but to those sending a jet of water about 10 meters wide that covers most of the street and sometimes the pavement too that dries up in about 10minutes.
I often see them on the ring roads and I can't help to wonder what's going on. What happened to saving water?
anybody have info on that ?

Yes,
they are hoping that the ringroad will grow to take up all the new traffic being generated by the 1000+ new cars registered everyday in Kunming.

In all seriousnous.
This is to keep down the dust kicked up, and added to, by the traffic. The dust itself will carry other particulate pollution on its surface. Watering washes the dust off the main carriageway, into the gutters and on, to the drains.

This is water taken up from local watercourses, which is not fit to drink. I would avoid breathing the aerosol droplets too.Most of the water ends up in the drains. and back to the polluted water courses.

Thanks tigertiger, I was thinking that might be something along those lines. I can understand why they would want to keep the dust down but the washing part doesnt seem to work as there is usually not enough water to actually wash anything away, its more like sprinkling the dust until it's dry and repeat...

So the tap water comes from the reservoirs and has nothing to do with the watercourses? I thought everything was treated and sent back to the running water system

There are at least 4 grades of water used in China.

Water for taps/domestic use. The used water is then re-cycled close to the user. At home this usually goes back to a collective tank for the property development, and is then filtered/treated. Commercial premesis often recycle their own. The water filter systems for commericial use can also have a recycle function.

Re-cycled water, used mostly to water plants in a housing developlment.

Surface water, from rivers canals, fit for agricultural purposes. This is used in agriculture.

Surface water, not fit for agricultural purposes. Used to stink up the neighbourhood, tranmitted through inky black, stinky waterways. From the smell sometimes I think they use this on the roads.

@tigertiger
I liked your first answer better...

Actually, I thought they were watering the roads to sweep garbage and debris to the sides.

All I really know is - if you are fortunate enough to hear the water truck melody - run for cover - riding bikes, e-bikes, or just walking on the sidewalk (or on the paved road as is customary for Kunming pedestrians), or even driving - wind up those windows or you'll be blasted with some truly unclean water. Be grateful they're not using that incredibly noxious barely recycled sewer water that they use around my apartment complex. That stuff is really nasty.

They have been doing do since I've been here (7 years already). When I first hear the music, I said to myself:" What the hell is that music?" They would play Happy birthday song or Jingle Bells.

I think they got the jingle out of a novelty greetings card.

The plan makes sense but the effort being made is fruitless because they dont spray enough water to flush dirt down the drains. As the original poster mentioned they only wet the pavement, 20 mins later it's dust as usual.

Ironically, the song is "How Dry I Am."