Rodding a rainwater drain

[Argentum66]

Overnight heavy rain has highlighted a block in my rainwater drain. I think it is 110mm (without measuring). The drain drops for about 70 cm from the grate before turning through 90 degrees. I have had a hose down for about 3-4 meters until it stops, switched on, but the water just backs up. The blockage must therefore be in this small bore pipe rather than the main drain.
Would it be possible to rod this drain from the grate i.e. are rods flexible enough to get around the first bend?
Is this the best place to rod from? The only inspection chamber I can find seems clear and other water is passing through it, so I figure the block must be in the small pipe and couldnt be cleared for the inspection chamber. Any help appreciated before I go and buy some rods.
Thanks.

 

[Hugh Jaleak]

Are you sure the drain connects to a sewer and doesnt go to a soakaway? The 3-4 metres you can get could be the distance to the soakaway, the heavy rain has simply caused the soakaway to fill, and the water is taking its time to drain away.

 

[Argentum66]

Hi Hugh

Not entirely sure that it is not a soakaway but have tried flushing water down the drains from the roof downspouts and the drain in question fills up. This would mean if it were a soakaway it would need to be clearing an awful lot of water quickly, so I suspect it exits to a drain somewhere.

 

[Burnerman]

Hopefully to help with the other question - normal drain rods won't pass around the gully trap - the only chance you've really got is to lift up the inspection chamber lids to see where the water is coming from, and rod towards the gully from there.
Drain dye is a great help when locating pipe outlets.
John

 

[Hugh Jaleak]

As John has said, rods wont go round a 90deg bend, if you forced them round you've got to get them back out again and straining rods usually results in the rods snapping. (Especially cheap rods!)

If you cant work out where the run goes then getting it jetted may be a safer option, and if the jetter wont shift it then usually time to start digging....

 

[Argentum66]

Hi Burnerman

Thanks for your reply. My problem is that I can see water running in the inspection chamber, but it is not from the drain I am concerned about as that is still backed up. I presume the blocked drain empties into the pipe leading to the chamber, but cant be sure. This also leads me to think the block is between the grate and the point where it empties into the drain connected to the inspection point, so rodding from the inspection point wouldnt work. The direction of the 90 degree bend suggests the pipe travels towards the house next door.