Backflow can occur in a drainage or plumbing system due to a number of different factors. As well as the common blockage, when the wrong items are flushed down a toilet, where there is nowhere left for the water to go, except for going back the way it came, is a burst mains pipe or an incorrect installation.
It can be an issue when the water pressure is not high enough to allow the water to flow as it should. In order to put this right, whatever the reason for the backflow, a drain inspection is necessary to determine if there are products blocking the system or if it is because of any other reason, as mentioned above.
You can prevent blockages from building up by only flushing the right things down a toilet, instead of items which are not meant to be disposed of in this way. Therefore, backflow will no longer be an issue for you.
Other preventative options for different scenarios within plumbing systems include installing backflow preventers like non-return valves to help with this. It all depends on the assessment of the situation and what measures are the most suitable. Speak to the maintenance experts on the best way to proceed.