Water leaks and overflows can cause an immense amount of damage and inconvenience. If water is dripping down the outside walls from your overflow please turn off at your stopcock and call a plumber.
If you are going to be away from your flat for more than a day or two turn off your stopcock as a precaution.
Regularly open and close your stopcock to keep it working properly – do not wait until you have an emergency before finding out that it is not possible to turn it off! We also (rather too often) get water from a leak inside one flat appearing in flats below. Part of the cause is the copper waste pipes which can be corroded by the use of some types of un-blocking chemicals.
On a different tack, DO NOT PUT FAT OR COOKING OIL DOWN YOUR SINK OR TOILET. It results in “fatbergs” blocking our underground drains – with unpleasant and expensive results!