Guttering / DW Waste Pipe Heavy Rain problem

[greatestdancer]

In my kitchen, I have a dishwasher waste pipe - it is routed into black pipe that runs from the roof (guttering) to the ground (outside). Normally this is fine, but if I get heavy rain, the pipe that both the guttering and DW waste pipe are routed into fills faster than it can drain away, and water comes back through the dishwasher waste pipe and back into the kitchen.

So far no-one has been able to propose a solution. I had a guy come over with a power-hose type device, he sprayed it down the garden-side of the drain; clearly this hasn't resolved the fault.

Another plumber thought the problem was that the drain pipe simply leads to a soak-away.

A third plumber had no idea.

The water board took a look, but suggested pretty quickly that the problem wasn't their problem.

What are my options here? I know that the drain that runs from the guttering to the ground has a hole cut in it, and that seems to direct some of the water (at least) out into the garden rather than straight down, but in heavy rain, that clearly isn't enough to avoid the water coming back through the DW waste pipe.

 

[rpm]

A. Is that legal?
B The pipe to the soakaway is restricted.
C Changes to the garden has altered things.

 

[Aquarius]

Please post a photo of where this arrangement is, and check to make sure that your dw pipe isn’t stuck too far into the downspout. If you have foul water (dw) going to a surface water drain or indeed a soak away, then as @rpm that will not be legal, and more so if water board haven’t picked up on it, then that’s pretty shocking, as they enforce the water regulations (contamination).

 

[greatestdancer]

Here's some more pictures. This is the outside wall adjacent to the kitchen. That grey pipe is the DW waste pipe which feeds into the drain pipe.

Here's the dishwasher waste pipe. During heavy rain, water just starts spraying out of the top of this pipe, hence bucket underneath. Worryingly, the power socket is just behind that bucket - how it hasn't hit the electrics, I'm still not sure.

One thing I think it's worth mentioning is that this has never happened with the DW running. The root cause has always been heavy rain.

When the water board came to assess the drainage, all they did was pour a jug of dyed water down the waste pipe, but the more I think about it, the more I wonder - in what way does that possibly simulate heavy rain?

In case it's relevant, I've also noticed that the sink isn't draining all that quickly either.

Lastly here's a video of the pipe during the rain:
View: https://www.youtube.com/watch?v=3rIIbPlVDsg


Any advice greatly received!

 

[greatestdancer]

I've checked that - only a very short part of the DW Pipe was pushed into the downspout, no more than 2 inches.

 

[Aquarius]

I've checked that - only a very short part of the DW Pipe was pushed into the downspout, no more than 2 inches.

2 inches? That’s more than half the downspout however I’m inclined to think that this maybe terminated into a gulley which I suspect is blocked. Have you a photo of where the downspout terminates?

 

[snowhead]

All the Water board were doing by putting dye down the drain was to see if it went to the Foul drain, which if shared with others is their responsibility.
Presumably the dye didn't go into the foul so it's not their problem.
The volume of water they used would only need to be small.
They would already have guessed, like some on here have, that the black rainwater downpipe goes to a soakaway meant only for rainwater.

Does the black downpipe come from a gutter for a small flat roof extension, if so the soakaway is probably only just coping with that amount of water.
If it is going to a soakaway it will need to be dug out and refilled with suitable material and the dishwasher waste will need plumbing to a foul drain.

You'll need a drain unblocking contractor to either jet the black pipe clear to the foul drain or trace it to prove it goes to soakaway.

 

[greatestdancer]

> 2 inches? That’s more than half the downspout

No no, the downspout before the kink is about 17 inches, only 2 inches of the dw waste pipe is pushed into the top of that.

I didn't fit this waste pipe by the way, it was there when I moved in. The waste pipe for the washing machine is elsewhere in the kitchen and must be OK because otherwise the heavy rain would back up there too.

I guess I need a drainage specialist to fit me a new (separate) waste pipe then.

Is it likely that the dw waste has blocked up the soak away then? How would you determine and/or resolve that?

 

[Pickwickpick]

Yep sounds like it's going to a soak away which your dishwasher waste shouldn't be connected to. You'll need to disconnect the dishwasher from the gutter downpipe and plumb into a foul water drain. The hole in the downpipe will need blocking off and if its struggling to cope with heavy rain the soak away will need redoing.

 

[PETE 123]

short term remove internal pipework run hose from dw through hole that waste pipe went through and make something up for it to go in the large pipe so at least no further floods.

 

[king of pipes]

Agree with the chaps above your dishwasher is piped to a rain water soak away which is not to regulations with the weather we are experiencing soakaways often cant cope with the torrential down pours of rain , kop