Blocked rainwater outlet.

[dan83590]

I need to unblock a rainwater drain. The downpipe is fitted into a drain cover that will lift off, access is good. With the cover off I have removed all of the leaves. There is a black cap pushed into an outlet into the drains. I removed this and the water drained away. Should this be there or was it forgotten by the builder before they finished?

What is it for?

 

[Hugh Jaleak]

If you have an 'Osma bottle gulley' then the cap is removed to provide rodding access in the event of the pipe from the gulley getting blocked. Water draining away once this is removed makes me think the bottom of the gulley is still full of leaves and/or silt, thus blocking it.

Plug not essential if the gulley is connected to a rainwater only drain, but if it's connected to a combined system (foul and surface water into same system) then the plug really needs replacing to prevent offensive smells escaping via the gulley.

 

[dan83590]

Excellent reply. Thanks.