Rainwater drainage connection

[pahars]

Morning all. I live in large victorian semi-dettached property. Between the two properties is one fall pipe running down onto my property linking into a standard square hopper 110mm pipe/p-trap then 110mm pipe into the main street drain. (distance from house to street drain approx 3m). No other connections go into this at present. No issues occur with light rain but any moderate/heavy rain causes the hopper to over flow. The pipe has been rodded right through to the main street drain on numerous times and the p-trap is clear so it appears that the p-trap/current setup cannot cope with the flow of water. I've been looking at replacing trap with a bottle gully. Any ideas if bottle gullies might cope with a higher flow rate of rain water? If not, any other suggestions?

[msh paving]

I would be surprised if it makes any difference at all,it is still a 4in pipe so flow the same MSH

[seanandruby]

Next time it rains and your gully overflows have a look in the main manhole to see if the water is getting away quick enough. a manhole should have the capacity to hold a surcharge of surface, or foul waste before it becomes a problem. If the water is getting away fine in the manhole then the problem is the 3 metre length100ml dia' pipe, either not capable of taking the volume of water or a back fall in the pipework. maybe upgrade to a 150 pipe. Is it a combined foul surface water drain? if so you may need to place seperate runs to the manhole.