How to stop water bubbling up through concrete patio?

[dihaveachat]

Hello, I would appreciate some advice on what to do next.  I have installed a few drains to assist manage excessive surface water coming from the neighbor's property and flooding our backyard.  It is extremely difficult to manage/direct the water towards stormwater drains or away from the home as we have a backward/negative slope. However, the drains I have installed have been successful in minimizing the damage/level of water in our backyard during heavy rainfall periods.  The neighbor refuses to install drainage on their property and happy for low lying water to sit for days or weeks.  I am worried that this fact is raising the water table and impacting on our slab as efflorescence is seeping through our front patio and evident on the brickwork.  I am considering placing drainage channel along the edge of the patio. However, I am open to ideas on what would be the best approach to minimize the level of seepage alongside the home. I've included photos of the front patio area where I thought a channel drain may assist??? Desperate and not wanting to install drainage in the wrong position or if it's not going to be an advantage.   

[JacobZ]

Hi @dihaveachat,

Welcome to the Bunnings Workshop community, it is fantastic to have you with us.

Drainage channels are only going to help with surface-level water, so if you are having issues with water beneath the surface, then a drainage channel isn't really the way to go. 

It can certainly help if you are getting surface water spilling over the patio, but it sounds like the issue is with water getting under the slab and coming up through it.

If anything, an additional french drain along the edge of the patio would likely be the way to go. If you can prevent the subsurface water from travelling sideways through the use of a french drain as close to the patio as possible, this would likely do the most good.

Do you have any photos showing where the water is coming from? This might help us offer further solutions.

Allow me to tag our knowledgable community members @Dave-1, @Nailbag and @R4addZ to see if they have any thoughts.

Jacob

[dihaveachat]

Thank you Jacob, I don't have photos of water impacting the front patio.  I have not sighted water streaming off the front slab.  The only issue I've sighted at the front is on the corner where the pit now tends to overflow during high rainfall.  I think the water is coming from the backyard/neighbor's property and travelling under the slab or soaking into water table running through the area.  I have heaps of photos of water at the back patio.  

[R4addZ]

Hi @dihaveachat 

I personally would call in an expert to determine where the water is coming from. If the neighbor is at fault then explain to the neighbor that if they don't remedy the situation, then you will at their expense. Sue if necessary! If it's not the neighbors problem, then at least you will know the real cause and how best to address it.

[Dave-1]

Good Evening @dihaveachat 

I am thinking of a deeper french drain, one that has a bottom below your rear concrete slab base. FIlled with largish gravel (12mm) and even then reusing your white pebbles along the top so everything will look as it does now but you will be removing the ability of the subsurface water to continue seeping down the slope and underneath the back of the house. 

You will need to make sure that the ag pipe can drain freely without pooling to a stormwater point is all.

Dave

[AlanM52]

Hi @dihaveachat,

I have a feeling before discussing remedial work there are more dots that need to be connected.

Have you lived there for a while and always had that situation and if so has it been consistent - has not worsened.

Is your system gutters/downpipes/stormwater all OK.

Did you have a eyeball over the fence to see if the lay of the land has changed, been disturbed in some way.

I don't see how that amount of surface water runoff can create the issues you have with driveway and house - something is sus.

Cheers.

[dihaveachat]

My problem with a french drain is that I don't have sufficient slope to direct it off our property.  The drain would remain below the surface, and unable to escape?? 

[dihaveachat]

Hello, our gutters/downpipes/stormwater are all ok.  Surface water runoff coming from the neighboring property has been a long term issue.  However, the past 3 years the situation has worsened possibly related to excessive rain event.  It was approx 3 years ago when I noticed the paint cracking and a little efflorescence on the front patio.  It was at that time, I implemented PVC drains to direct the water away from home and yard.  These drains definitely help (and with a little more redesigning after rain events) only the garden area in the backyard is now impacted.  The neighbor allowed bush turkeys to build a nest collecting mulch to a height of 1m and length 3m.  This may have contributed to the excessive runoff water/flooding our yard, however it would in the back section and the water travels through the middle of their property.  The neighbor has now cleared the nest and their yard the same as it has been for many years.  

There is less surface water running into our yard; however the runoff water is sitting longer in their yard as it escapes through the drains I have installed.  

Thanks for thinking of a solution

[MitchellMc]

Dealing with natural water flow between properties is always difficult @dihaveachat, and it often ends up being something that each household has to manage on their own side. Unless the neighbour is doing something that actively collects and redirects water onto your block, there is usually very little they can be compelled to change apart from installing their own drainage. If you feel the situation is excessive or worsening, it can be worth speaking with council because they may be able to offer guidance, particularly if your property sits in a natural low point.

From what you are showing in the photos, the efflorescence and the cracking you have noticed on the slab can also be attributed to age. It is not unusual to see this sort of surface damage even when drainage is otherwise reasonable, so it does not necessarily mean there is a serious structural issue developing. It often reflects the exposure and age of the concrete rather than ongoing harm.

The real long term solution is still going to be improved drainage. If you cannot create fall to direct a French drain out to the front, it is worth checking whether there are any stormwater lines within your property boundary that you could legally and safely connect into. That would allow the water to enter the system without relying on natural slope. If that is not an option, you could consider having a large soakwell installed. A soakwell gives you a dedicated place for the water to disperse, and it can be buried under turf or a garden bed so it does not impact the use of the space.

In terms of the water table, it generally is not something that a single neighbouring yard can raise unless you sit in a naturally low spot where all the runoff wants to collect. If you suspect that is the case and that your property is being significantly affected by the surrounding blocks, that is another reason council may be worth contacting. They can look at the overall fall of the land and advise whether anything can be done to help manage the drainage more effectively.

Please let me know if you have any questions.

Mitchell