Wasting water

One of the things I will always criticise to hongkongers is how they waste water washing the building stairs with water, lots of water every time they clean it. It is the samewasting when cleaning the street with the public service; lots of water from my point of view.
It is true that there is water in Hong Kong, but anyway it is necesary to expend energy to move the water, in addition to the wasting.
In my opinion, they could clean the stairs much better with little quantity of water in a bucket, just as mopping it energetically.
But what we can do? In some way, it is something cultural.