The Brew Cabin

I have recently had a conservatory installed, dimensions 4mx 3m, a single down pipe was installed to handle the roof water. I have opted to use a collapsed / disused air raid shelter approx. 15 metres away from the conservatory to form the soakaway and potentially introduce another down pipe from the main house roof. Current plan is to install an open gully/ drain at the bottom of the gutter system.

There is a slight gradient up towards the proposed soakaway, could you please advise the best way to link the gully to the soakaway e.g. what pipe would you recommend perforated or solid or bit of both? , How deep should the trench be?

My primary aim is to ensure that water does not collected in and around the conservatory foundations and undermine them over time.

Any comments or suggestions would be gratefully received.

Using a perforated pipe would allow it to act as a land drain for the patch of ground between the conservatory of the intended soakaway, which may, or may not, be a good thing, depending on ground conditions. If you have well-draining ground, it could act as a dispersal drain and so ease the laod on the soakaway, but, if you have wet ground, it will act as a collector and thereby increase the load on the soakaway.

A solid pipe is easier to maintain, but slightly more expensive for the total construction. It will simply take all the collected water from the downsput straight to the soakaway, with so additions or subtractions. If you have variable ground, or ground that's wet in winter but dry in summer, this might be the best option.


Depth is dictated by the levels you have on site. The highest point has to be where the surface is collected, at the downspout(s). Remember, if you're using a gully or a P-Trap and hopper, you can set the outlet level to suit site conditions, but it's generally somewhere around 150-300mm blelow surface level.

Then you want a steady fall to the planned soakaway, something around 1:100 would be fine, so that's 150mm over the 15m. You can, of course, put more fall on the connecting pipe, if you wish, or plunge the first couple of metres so the pipe level drops from, say, 300mm below ground level (GL) to 600mm below GL and then reduce the gradient to 1:80 or 1:100.

It's also a good idea to ensure you have access to the pipeline one way or t'other. This might be achieved by using access fittings at the downspouts, or incorporating a Rodding Eye at one end of the pipe run. This will save you having to force access from the soakaway pit or dig up the patio if ever there was to be a problem. :)