It depends on what is causing the blockage to come back time and again as to how it has to be fixed.

Tree/plant roots can only really be solved by digging up the damaged pipes and replacing them. A plumbing snake will only ever push the roots aside clearing a tiny hole that will quickly block up again. Where I work we had two urinals that were constantly blocking up & overflowing. In the end they took the pipes out and replaced them, and we had a 4cm diameter pipe 4 meters long with a 3-4mm hole down the middle. All the plumbing snake had been doing was making a hole (10% of the size of the pipe) through the blockage, the blockage was never actually removed.

I have also heard that excessive use of laundry detergent tablets can cause a problem, as the detergent re-solidifies in the pipes as the water cools. DO not know if this is true or not.

My problem was/is a kitchen sink (1st floor in a block of flats) that was also served a dishwasher and washing machine. It would run clear and free for years, only to suddenly block up 4 times in a week, for no apparent reason, with no change in behaviour. The only solution I have found is one of the very aggressive sulphuric acid based cleaners that carry a seriously worrying health warning. I suspect my problem is caused by the above mentioned "bad bends." The section of pipe visible above the false ceiling below is straight. I can not look as the last 30cm of the pipe as that is encased in a concrete support pillar that hold the block of flats up, and would require some demolition to get to, and use of "snakes" never works, as the get to the bit of pipe that is not visible, and then jam, blockage unsolved.

It depends on what is causing the blockage to come back time and again as to how it has to be fixed.

Tree/plant roots can only really be solved by digging up the damaged pipes and replacing them. A plumbing snake will only ever push the roots aside clearing a tiny hole that will quickly block up again. Where I work we had two urinals that were constantly blocking up & overflowing. In the end they took the pipes out and replaced them, and we had a 4cm diameter pipe 4 meters long with a 3-4mm hole down the middle. All the plumbing snake had been doing was making a hole (10% of the size of the pipe) through the blockage, the blockage was never actually removed.

For my kitchen sink that also served a dishwasher and washing machine, it had run clear and free for years, only to suddenly block up 4 times in a week for no apparent reason. The only solution I have found is one of the very aggressive sulphuric acid based cleaners that carry a seriously worrying health warning.