Egyptian way of cleaning tower blocks

When I first saw it about a month ago, I thought a washing machine pipe had burst at the top floor of the tower block. However, the same thing happened a couple of days back and now I am sure this is the way my doorman and his family clean the "common parts" (stairs and floors) of the tower block.

Basically, they turn on the tap at the top floor of the tower, mix the water with various detergents and then let if flow all the way down to the ground floor. It is fun :) The water sometimes flows into my appartment with a fair amount of foam rising from under the door. But at least, alhamdulillah, the stairs are clean at the end of it.