All of my roofwater is directed into rainwater tanks. From there it is piped under the battleaxe entryway and is directed into a council inter allottment stormwater pipe which was installed by the developer of the estate. The grated pits in the driveway seen above catch driveway runoff and direct it to the same pipework. No water will be directed into neighbours property.
kudos to you. i have been following your post regularly and i respect your innovative ideas in development.
out of curiosity - what is your background as in profession previously from being a developer?