Can Main roof guttering to discharge to a lean to roof?

[zachmbutcher]

I’m planning to install an en-suite and the new waste pipe can go into the combined drainage by utilising the existing rainwater Down pipe. As such I need to move the existing rainwater down pipe.

Can I move the down pipe from its existing location to the far side (green line in picture) and run it down to another existing pitched roof on a small extension? (Obviously observing the necessary fall for the water direction)

Are there rules about this? I can’t see anything. And my old mid terrace house (new build) did this on to a porch roof.

Will the water from the larger roof overwhelm the small roof and guttering on there?

 

[Harry Bloomfield]

I’m planning to install an en-suite and the new waste pipe can go into the combined drainage by utilising the existing rainwater Down pipe. As such I need to move the existing rainwater down pipe.

Are you sure that rain water, and grey water really are combined? Many areas have these services separated, and you can be fined, for discharging into the wrong one.

 

[zachmbutcher]

I have been in touch with United Utilities and they have confirmed they are combined, I guess I can do a bit more to confirm it

 

[zachmbutcher]

Are you sure that rain water, and grey water really are combined? Many areas have these services separated, and you can be fined, for discharging into the wrong one.

I have been in touch with United Utilities and they have confirmed they are combined, I guess I can do a bit more to confirm it

 

[ChrisJP]

If your drainage is indeed combined, why do you need to stop the gutter draining into the drain pipe you plan to use for the ensuite?
Will the ensuite have a toilet as well as a shower or bath? If so, the smaller bore rainwater pipe you plan to use to drain the ensuite will not be of sufficient diameter to cope with the "solids" that will enter it.
If you do move the gutter drain pipe to the new position indicated in green, then you may need to alter the gutter fall to ensure rainwater drains in that direction.

 

[zachmbutcher]

If your drainage is indeed combined, why do you need to stop the gutter draining into the drain pipe you plan to use for the ensuite?
Will the ensuite have a toilet as well as a shower or bath? If so, the smaller bore rainwater pipe you plan to use to drain the ensuite will not be of sufficient diameter to cope with the "solids" that will enter it.
If you do move the gutter drain pipe to the new position indicated in green, then you may need to alter the gutter fall to ensure rainwater drains in that direction.

The existing rainwater down pipe would be changed to a waste pipe suitable for a toilet waste

based on another thread response which advised toilet gasses would rise up the drain and in to the eaves so moving the rainwater to the green line frees up the location for the new waste pipe.

 

[ChrisJP]

Ahh...I understand now.
I can't see any objection to moving the rainwater drainpipe to the green line, though letting it drain over the flashing and extension pitched roof will potentially cause unsightly staining on that roof, and may possibly eventuallu compromise its water-tightness. You could run a pipe down the roof instead to discharge into the extension gutter.
And, as I said, you'll need to look at whether the fall on the main house gutter needs adjusting to get all the rainwater to flow to the extreme end rather than flow to the middle as it now does.