every house got water tank at the roof top.... consider this bad fung sui..?

Those rich who bought it may not be living there often, it is just part of their asset property as this type design is the current trend. They can live at where they feel is good FS, of course those practice it, many of them actually practice or utilising FS in a low profile ways. Water is an element which is very unique, Water can go to where even a super tiny channels. It is flowing down unless forced to go up. The Qi can seep through any tiny holes. Do you think you will get Health problem? Rheumatoid arthritis, or something...In long run. Wealth palace is just part of the Life, in which there are 11 other Palaces like Health, etc.

Well speak of this TL project, there are at least 2 serious incidents happened before,  those owners or residents living there surely know about it.

FS effects may not necessary bring you Wealth problem at first, do not get wrong, it can affect your other aspects of life initially and gradually e.g. Health or Accident, etc until then your Wealth is diminishing due to all those problems. It may take weeks, years or so depend on the owner personal elements or luck. By that time, it may be too late to do anything.