BLOCKED DRAIN

[Jeff613]

My final sewer drain with the U bend (ie the drain immediately before the exit from our garden to the road) constantly gets blocked. I use my rods to free the blockage. There is no discernible reason for what is causing the blockage and we are very careful. Anything I can do to help prevent future regular blockages?

 

[Gasmk1]

There must be a reason best to get it surveyed