How do toilets without tanks operate (like the kind in office buildings)?

Question

How do toilets without tanks operate (like the kind in office buildings)?

Answer 1

They still have 'tanks', the cistern is normally hidden behind the wall panel for neatness and to stop vandalism

Answer 2

Office buildings usually have water storage tanks on their roofs to provide the necessary water pressure. Now-a-days the more modern buidlings even have solar heating and hot water systems on their roofs as well.

Answer 3

In the U.S., most are connected directly to the water piping and the flow is controlled by a flush valve (Sloan valve is most common).