The majority of leaks can be traced to a standing pool of water somewhere in the home, a level floor should fix that
If you happen to find a leak coming from a balcony, or from beneath a wet area such as a bathroom, you would need to remove any architectural finishes (such as tiles), and redo the floor (in a manner similar to repairing a wall) to ensure that any standing water flows into the discharge outlets.
Once you have removed tiles and exposed the cement floor, you would need to level the floor so that any water that ends up there finds its way out. If the cement floor is patchy or dipping in some areas, you would need to hack out some of that floor and replace it.
Putting cement into the joints between horizontal and vertical surfaces would help to prevent water from seeping in between walls and floors. Mix up a batch of cement, throw in some plasticising additives such as latex, and form little ramps between walls and floors before levelling the floor.
Check that water flows into discharge outlets before replacing your architectural finishes (such as tiles).
This article is intended to convey general information only. It does not constitute advice for your specific needs. This article cannot disclose all of the risks and other factors necessary to evaluate a particular situation.
Any interested party should study each situation carefully. You should seek and obtain independent professional advice for your specific needs and situation.