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Need advice for backyard drainage solution

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Need advice for backyard drainage solution

I am trying to create a longterm solution for backyard drainage. The backyard is not done yet but I want to do the drainage right first. My plan was to create a french drain connected to a pit to catch the silt then have it connected to existing 90mm storwater pipe. Also planning to have an overflow pipe positioned higher and going towards the fence into an exisiting AG pipe drain to safe discharge point. However, my question is:


With the signifant amount of water collected in the yard, will it overload the existing 90mm downpipe towards the 100mm dwv stormwater pipe towards the kerb? I am worried since this whole area will be concreted later on and might cause any problems in the future. What is the best approach for this?

I asked a plumber as well and said that as long as the pipe you are connecting to is on slope and not holding water then it should be fine.


Looking forward to your advice.




Bunnings Team Member
Bunnings Team Member

Re: Backyard drainage Solution

Hi @Gio-Tan,


It's great to have you join us as part of the Bunnings Workshop community.


It looks like you've already got quite a thought-out plan in place, and I would agree with your plumber's assessment that the most important thing is that everything has enough slope to run off in the direction that you want it to. A French drain running perpendicular to your house at the bottom of the slope is a great solution and will do a lot of good in this situation. Channel grates, running along the edge of the house will also do a lot to move the surface level water away from your home and out into the council stormwater channels.


As plumbing is a licensed and regulated industry, I would suggest the best person to speak to around the capacity of the downpipes and your proposed drainage would be a plumber. They can give you advice based on their own experience and interpretation of local standards and practices as well as local knowledge that our members would be unable to give.


If you are looking for a bit more guidance on how best to address drainage issues, I might point you towards these helpful articles from the Bunnings knowledge base:




If you have any further questions, please don't hesitate to ask.



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