How to fix stormwater issues?

[Wintermute]

Hey all,

looking for some advice regarding a stormwater issue around the house.  First, when it rains heavy like it has recently, the downpipe at the connection to the in ground pvc backs up and pours out around the fitting.  There is another pit in the middle of the paved area nearby but don't like the idea of water backing up against the exterior wall..  Is this the correct way to connect the downpipe or would a grated pitt work better?  I think the ground pipe is clear and flowing ok I checked at the inspection cap.

The bigger issue is under the house, the previous owner dug out a hole in the sandstone bedrock.  During heavy rains the hole fills with water that comes through pourous areas in the sandstone up slope. It does drain quickly within 24 hrs after.  I want to level it out and add pavers how do I divert the water away from under the house?  I believe its a bit lower then at the front corner of house where I can connect to a stormpipe running down the side of property.  Is it worth contacting an Engineer to find a solution and leaving this to the pros?  Thanks in advance.

[EricL]

Hi @Wintermute 

Welcome to the Bunnings Workshop community. It's sensational to have you join us, and thanks for sharing your question about your stormwater. 

In this particular instance, I strongly suggest engaging the services of a licensed plumber as they will be able to recommend the proper method to divert the water coming into your property. At this point in time, I don't recommend making any changes not until you've had a discussion with the plumber. In regards to your assessment, I agree and think that the downpipe is not being overwhelmed with the amount of rainwater coming through. Perhaps extra outlets might need to be installed on the gutter to reduce the volume of water passing through.  

The water gathering under your house is not a good sign and could damage the foundation of your house. It would be best to divert this water away before it begins to puddle.

Let me call on our experienced members @Dave-1 and @Nailbag for their recommendations.

If you need further assistance, please let us know.

Eric

[Nailbag]

Hi @Wintermute 

You don't need an engineer, just a decent plumber and possibly one that has an inspection camera, as there is a definite break somewhere under the house. These cameras are feed through the inside of the plumbing pipe to see where blockages and/or breaks are in the system. Other then the need for a quick DIY repair in this case, legally your not supposed to do any plumbing work yourself.

I would get on to this pretty quickly.

Nailbag

[Wintermute]

Hey thanks for your responses. Just to clarify the ground stomwater pipe is functioning and mostly above ground under the house and not the cause of the flooding.  Its just that in this one location during heavy rains the water overflows around the connection.  I thought using a pit and cutting the downpipe would fix this...

As for the flooding in the undercoft its most likely ground water as the site is steeply sloped and mostly sandstone.  I'll contact a plumber and see what they say.

cheers,

[EricL]

Hi @Wintermute 

Please keep us updated with your progress, we look forward to seeing your stormwater drains upgraded and functional.

Eric

[Dave-1]

Morning @Wintermute 

You could have a partial blockage of leaves that is in the piope leading away form the downpipe, so showers ect it drains but when it pours then it cant handle, A plumber as you have decided is a good place to start with (they will have a camera and a water cutter jet for sure)

The area under the house, Im with the divert the water away before it gets to your indoor pool, Id also be tempted to add drainage away from the area if possible before backfilling with gravel and paving.

Diverting the water, at least the surface water could be simple as an erather berm further up the slope under the house to a concrete dish drain and then stopping side access from entering. Looking at your first photo it looks liek you may have tried that earthen bank idea already? or Is that just a retaining wall? 

Dave

[Wintermute]

Hi Dave,

I've called a plumber to take a look at the issues.  Its a bit tricky knowing where the water is coming from upslope as there is no surface signs of water logged areas...there is a raised grassy area behind the house that probably drains quickly as I suspect its built over rubble.  The rear neighbour property is also raised up about a meter behind fence.  Looking at the old sewer plans I think there is an old disconnected clay pipe that runs along back of house.  If this is broken could it convey stormwater underground?

thanks again

Rob

[EricL]

Hello @Wintermute 

Let me tag @Dave-1 to make them aware of your query. In regards to your question about the clay pipe, its best to ask the plumber or perhaps do a little research in regards to existing storm water drains under the house. There is always the possibility that the clay pipe is still viable and can be used for drainage. 

Eric

[Nailbag]

Hi @Wintermute 

Stormwater and sewer are two seperate lines, so it's highly unlikely to be the cause. Ground water can be very difficult to establish and resolve. I used to live on the side of a mountain and tried so many different methods to stop under my house flooding similar to yours. I found out the mountain also has=d countless underground streams to add to my issues. In the end I installed a pit in the low collection point with an automatic submersible pump. When the water got to around 40mm the pump started up and transfer the water to the stormwater system.

Did the plumber fix the overflowing downpipe/s?

Nailbag 

[Dave-1]

Good Morning @Wintermute 

A lot of water can be subsurface water, and yeah I hadnt realised how much water drifts downhill while under the ground and how fast it can go. I had a hard surface side path and had water entering under the house. When I dug up the concrete side path to install the stormwater pipes plus gravel in teh trench is when I realised how much water would travel under the ground. By installing effectivly a french drain down the side of the house and not concreting over the top I created a channel that carries water away. So no more subsurface water under the house.

Stormwater rectification stage 1 

Stormwater rectification stage 2 

Are the projects for fixing my issue. Stage 1 is probarrly better to show you the square drain and gravel. When I go to replace the concrete path at the back of the house I will be doing the same and I know it will stop even more subsurface water from flowing down the hill.

So you could do a drain that will do both, subsurface and ground water along the back of your house. The terracotta pipes could be stormwater but probarlly may be old sewer pipes (check with the plumber for their ideas as they know a LOT more then us, especially for your area.

If you did a french drain with a large agpipe plus inspection points to clean out if needed) across the rear, and added in a grill drain on top then it would lower the amount of water making it ro under the house whichever way.

Dave