We have observed that there are no water tanks on the roof in most of the apartments.
Then my question is how such a high water pressure is maintained so that the water flow is not impacted in our household or in any high rising office?

Even if they have a pump below the apartment is it running 24/7??

Your thought please..

You'll probably find there's a gym very close by, with cheap membership .....

In Germany the city is obliged to pump the water to the 6th floor. For higher buildings the builder has to install an extra pressure pump.

How it is regulated here I don't know.