Yes, the water just disappears into that blacktop in the video above. And it’s not just a cool trick, either. Two-thirds of buildings damaged by the Midwest floods in 2007 were hit by water rushing off pavement or out of overwhelmed drains. Permeable paving could be a way to save countless homes from flash flooding.
Where does all that water in the video go? Depends. According to the product description, it can simply soak into the soil beneath the pavement or into installed drainage.
Permeable concrete can also help maintain local water quality by blocking the absorption of larger particles at the surface and trapping finer materials, like hydrocarbons and heavy metals, as they percolate through lower layers. The cleaning effect can be amplified even further with the addition of a geotextile membrane.
The concrete also has another use: Urban roadways suffer in the summer from something called the “heat island” effect, where the dark surfaces absorb solar radiation and then generate additional heat into the surrounding air. A surface’s ability to reflect solar radiation without generating heat is called its “albedo.” Permeable pavement is lighter in color, with a higher albedo than asphalt. So another win there.