There are sprinkler systems designed to accommodate whatever water situation you have. I recommend that you make adequate research about the exact kind of water issue you may have before making a decision.
If your flat does have water but there isn’t much of it, best to opt for HL2 mist systems. They are self-contained and are ideal for where water supply is not available. They also do not require electricity or a main water supply to function efficiently.
However, if your concern is not the availability of water but where to store it, the BBK sprinkler system will be a more ideal choice. These systems work best where there is access to a water source but no storage facility.
Both the BBK and HL2 systems are very easy to install (in less than a day) and easily be moved from one location to another.