Running shower waste to rainwater downpipe on combined drainage

[cr0ft]

Hi all. For cosmetic reasons I would like to run a 50mm shower waste pipe directly into a 68mm rainwater downpipe at first floor level. There is a stack on the opposite side to the downpipe but it will look messy running the shower waste pipe around the drainpipe to meet it. Moving the downpipe is not an option.

The drainage at the property is combined and the downpipe flows into a gully and into 110mm PVC drainage pipe underground. Is there any reason why I can't do this? I know that conventionally they run into soil pipes directly but logically with a combined system I can't see anything wrong with doing this. The downpipe vents at the gutter (obviously) and is high enough above the upstairs windows to avoid smells coming back in.

Also, does anyone know where I can get a 50mm to 68mm boss connection for this?

 

[Nostrum]

No trap?

 

[cr0ft]

Smells from the hopper I guess coming back into the house, had one in my old house, they do smell a bit after a while! The drainage will be trapped at the bottom of the rainwater downpipe but the hopper itself might start to smell. I will put it to the customer and let her choose what she wants on the front of her house I think!

 

[tom609]

You wont get smells coming from the hopper head as you have internal traps

 

[Howsie]

And you have a trapped gully.