Check it monthly
Once a month, look it over for leaves, and confirm it's still draining after rain without sediment building up on top.
How much water it takes
Water permeable concrete, and how much rain it really takes
No rain event in Australia asks the surface to work as hard as it's built to. Permcon's wearing surface will pass 8,000 to 10,000 mm/hr; the number that decides your job is what's under it, the base and the ground it sits on.
Reading the 8,000 to 10,000 mm/hr rate
Leave the fines out of a concrete mix and what's left is aggregate held together by cement paste, with 20 to 25 per cent of the finished slab made up of connected voids running from the top of the slab to the bottom. That structure is what lets the number above move through. It's a rate, in the same units the Bureau uses for a storm: millimetres for the depth of water, an hour for how long it takes to move. No downpour in this country comes anywhere near it. Rain that lands on the surface doesn't sit there deciding where to run; it keeps going down. Read more about how the material's put together on our permeable concrete page.
Where puddles simply don't form
Water permeable concrete gives every drop a way down the moment it lands, at the exact spot it lands, so nothing needs to travel to a grate, and low corners stay dry. A sealed slab can't offer that: rain has nowhere to go but sideways; it crosses the surface toward a grate or the kerb, and every trowel mark and low point holds some of it back until it's a puddle. There's no sheet of water at the front gate here, nothing to step around getting out of the car.
Where the water goes under water permeable concrete
Cleaner water, too
Rain crossing any paved surface picks up oil, rubber, grit and dust as it goes. Push it through Permcon and the screenings underneath, and up to 70 per cent of what it was carrying, heavy metals, hydrocarbons, detritus and suspended solids, stays behind rather than reaching the drain.
What's left keeps moving into a bed of clean screenings under the slab, and that's where a storm is actually managed. Every 100 mm of that bed stores 28 litres under each square metre at 85 per cent design capacity, so going deeper buys room for a bigger event. From there it either soaks into the ground or bleeds out slowly through an under-drain.
Sand takes water about as fast as it arrives, so the base underneath rarely fills. Clay is a different job: the base holds the storm back and the under-drain releases it at a controlled rate, so the surface keeps draining on the day while the site as a whole lets the water go gradually rather than all at once. We work that depth out at a site visit, against your soil and whatever your council wants held back. A typical permeable concrete driveway lands around 37 to 42 litres of storage per square metre; the build-ups we use for paths and car parks are set out on the technical page.
What keeps it permeable
No soil, no silt
Keep garden beds and bare ground from washing soil onto the pavement, since silt, not rain, is what clogs the voids.
Once a year
Give it a sweep annually if the monthly checks haven't already covered it, and clear any moss sitting in the voids.
Bring it back with water
Washing is one of the ways to keep the pavement clean, alongside sweeping or a leaf blower.
Questions about the water
How does it handle a downpour?+
It won't be the surface that struggles. The real limit shows up in a long, heavy event, when the question becomes whether the base fills faster than the ground, or the under-drain, can carry it away. That's the number we size to your soil and to whatever storage your council specifies.
What if I want to drain a roof or slab onto it?+
Only if it's designed for it. Roof or sealed-area runoff needs more base storage; bare ground brings silt that clogs the voids. Tell us the source at the visit. We will work with anyone that wants the Permcon product, we just need to make a design that suits their needs.
What tells me the surface has stopped draining?+
Stand outside next time it rains. The water should vanish exactly where it hits the surface. If it starts pooling, or running toward a low point instead, sweep or wash the pavement to clear it.
Tell us the site, we'll size it
Give us the soil type and the area, then tell us where the water currently goes. Let us know what your council wants held back. We'll walk the site and come back with the depth your base needs to be.
Check your ground first
Check if permeable concrete suits your site
A few quick questions about your site. You get a straight answer about whether permeable concrete is the right call, including when it isn't, before anyone asks for your details.
Site check · 1 of 5
What are you surfacing?
Enquire now
Tell us about your project
Tell us where the site is and what you're planning. An estimator from your state team will call you back, look at the site with you and give you a real figure, from a single driveway to a council car park.
📞Call us1300 010 499✉️Email us[email protected]
📍Head officeFactory 7, 25-39 Cook Road, Mitcham VIC 3132
Where the rain goes through
