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Need to drain groundwater reemerging from dirt slope under the house

New Contributor

Need to drain groundwater reemerging from dirt slope under the house

Hi all, I’ve got a dirt slope under the house that has groundwater coming out of it after rainfall, washing dirt and bits of rock down onto the concrete floor of the workshop. There are piers all over the place and the slope is uneven, making it hard to find an obvious path to divert the flow using ah pipe, and I don’t want to go digging because of the piers. Any thoughts or suggestions? Cheers! Jim


Bunnings Team Member
Bunnings Team Member

Re: Need to drain groundwater rmerging from dirt slope under the house

Hi @jbs1,


You might like to show us some images of the area so our members can get a better idea of what solutions they could suggest. Would you be able to run an Everhard EasyDRAIN Polymer Grate & 3m Prejoined Channel along the edge of the slab to a point where Vinidex 50mm x 10m Black Slotted Draincoil could be connected, diverting the water out of the area? That would only require you to dig a small trench. 


Let me mention @Adam_W and @TedBear to see if they would like to join the discussion.


I look forward to hearing more about the situation and providing a solution to your issue.







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Super Contributor

Re: Need to drain groundwater rmerging from dirt slope under the house

Hi, my initial thoughts are.... where is this water actually coming from?  How long for/is it a relatively new thing?

On the theme of 'Prevention is better than cure'   it may be worth trying to see why a stream of ground water is coming toward you.


I had a similar issue in a house many years ago, where a room had been added lower on the block - i.e. it was a step-down room below the house's normal floor level, with a concrete floor. That house was on piers too. After removing smelly carpets after every winter, I eventually found that the driveway crossover at the front of the house (high end of block) wasn't installed correctly and was directing masses of street water into my drive which turned into a shallow stream under my house, came through a crack in the brick wall end of the added room and ended up seeping under my carpets. By the time I smelled it, the stream had always dried up. The council fixed it once informed, and I had no more trouble.

That may not be your situation, but the earlier in the system you can divert that water, the better your result will be.

I am interested to see more on what your own situation is...

Trusted Contributor

Re: Need to drain groundwater reemerging from dirt slope under the house

Hello @jbs1 


Welcome to Bunnings Workshop! I am a firm believer of DIY channel drains. I strongly believe in working with nature and not against it. So my solution for you is a two step approach. First I suggest creating a shallow U shaped water drain. It's also know as a spoon drain.


- Prepare your proposed area of the channel by creating a shallow channel about 30mm deep and then flattening it out with available garden tools. Use a level to make sure that the fall of the earth points out towards your nearest garden.

- Once you've prepared the ground you can use Bastion builders mix to prepare a cement channel about 150mm wide and at least 20mm to 30mm thick.

- Use a 2 liter bottle of coke or similar shaped bottle fill with water to prevent crushing the bottle, push down in to the wet cement channel to create the shallow U shape. Finish and feather to desired shape.

- While waiting for your cement to dry, visit your local Bunnings and buy some buffalo turf to cover the bottom area of your slope. It does not need to cover the entire slope just half a meter past the body of your diy spoon drain.


What is the turf for? The buffalo grass serves as a natural water buffer before it hits the spoon drain. The grass traps the water and the debris acting like a natural filter. Buffalo grass is very tough and hardy even in the shade so in essence if the grass survives then it should soak up incidental water. But should you get big rain then the spoon channel will redirect it to the garden. A winner in both situations, please note that in the drawing I've drawn the drain as a curve that is to just illustrate that you can build it with the turn and contour of the earth and does not need to be straight. Just remember that the edge of the drain must be level with the earth otherwise the water will just go past it and under the drain. I hope the drawing makes sense and helps you out.






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