No, a French drain isn’t one that plays “La Marseillaise” when you hit the flush button. But if you’re struggling with drainage in your yard, a French drain system might very well be the easiest and most attractive solution.

What is a French drain, anyway?

To look at a French drain, you might just mistake it for a pretty rocky garden path – and that’s just one of the best things about it. Even better, however, is that it will solve your garden drainage issues, whether it’s a storm or groundwater that’s causing all the trouble. Best yet, your home and structures’ critical foundations will be protected from erosion and flooding – and all with French drains that are easy to implement, more than pleasing to the eye, and really do work.

So how does a French drain work? In a nutshell, a simple yet clever array of perforated pipe built into sloped sub-surface trenches is finished off with landscape fabric and decorative gravel or stone top layer. But the versions more along the line of Henry Flagg French’s old-school and innovative 19th-century configuration can still get the job done in the form of nothing much more than a rock or gravel-filled trench, even if it might clog more easily than a more modern layout. But whichever way you go, for function meets garden beauty, there’s nothing quite like a French drain to:

  • Protect your foundations
  • Serve as a permanent and low-maintenance drainage solution
  • Look great with seamless landscape integration
  • Full versatility
  • Easy & cheap installation.

And while most plumbing & drainage work across Sydney and beyond will require the mandatory and skilled workmanship of fully-licensed Sydney plumbers and drainage specialists, learning how to install a French drain really is something you can DIY. Here’s how:

1. Prepare

The most important thing to know before you get started is precisely what’s laying below that garden surface. Because hitting a pipe, electrical line, or another underground cable, pipe or installation isn’t just going to muck up the smooth running of you and your neighbours’ places – it can be extraordinarily dangerous.

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2. Follow the rules

Are you sure any zoning or runoff regulations aren’t going to spoil your French drain party at a later date? Yet another precaution to check off the list is whether your proposed drain configuration isn’t going to cause drainage issues for your neighbours, because both of these issues can land you in hot and expensive water.

3. Find a downhill slope

It may be a clever drainage innovation, but a French drain is still incredibly simple and only works if gravity is on your side. Remember, the whole idea is that water is going to seep into your laid pipes and be carried away thanks to the downhill gradient, so:

  • Identify the drainage area
  • Start at the highest point
  • Route your downhill drainage route
  • End the drain where you want the water to go.

If your land is dead flat, you’ll have to create your own downhill trench by digging it shallowest at one end and progressively deeper with at least a 1-2% grade.

4. Dig the trench

You’ll need it about 30cm wide and half a metre deep, and make sure you don’t spoil the land’s natural downhill gradient with a poorly-dug trench.

5. Line it

Your French drain will be lined with fabric – but it needs to be one that is fully water-permeable. We recommend genuine landscape fabric which is designed with precisely this purpose in mind, and it’s installed by:

  • Rolling it out over the trench
  • Leaving a 30cm gap on both sides
  • Applying pressure to fill the gaps
  • Fixing it in place

6. Add the gravel

Now, pour a 5-10cm layer of gravel on top of the fabric.

7. Add the pipe

Any pipe will work, but PVC will last the longest and work the best. It will need to have holes or perforations to do the drainage work, and those holes should be laid face down and then the whole thing covered by another thin layer of gravel to within 5-10cm of the top of the trench.

8. Finish up

Complete your French drain by folding the remaining fabric over the gravel, and complete the system by covering it all up with soil. You can then creatively finish off the aesthetic look in whatever way you like, including planting grass or simply laying some decorative stones.


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Need help with your French drain system?

Every time it rains and pours across Sydney, we are all reminded about the importance of efficient, professional stormwater drainage solutions that protect your home, family, garden, investments – and sanity!

The suburbs of Blacktown, Engadine, Castle Hill, Casula and Penrith are some of the most effected by flooding according to NRMA, but nowhere is immune. If you want to put your French drains in the best possible hands, give Sydney’s friendliest drainage experts right here at Rapid Service Plumbing a shout.