22 gigalitres of stormwater runoff enters Sydney’s rivers and harbour every year. It can be a significant form of pollution, but could be a resource retained to water our trees and gardens. And the easiest and most cost-effective way to do that is leaky drains.

Yes, drains aren't typically supposed to leak! But for the residents of Chippendale it's been a great advantage and their Sustainable Communities Plan now argues for leaky drains to replace most unleaky ones in the suburb. Here's how it happened. Chippendale had no money to irrigate its road gardens, few houses had hoses out the front, and it seemed certain that plants would die from lack of water when people lost interest in gardening or became too busy.

One day, Michael was looking at the road, then the footpath and then the buildings. How, he wondered, could he undo the damage being done by the road to the soil in the verge? All city roads are designed to get rainwater away from footpaths and buildings as quickly as possible. Then Michael had an idea: why couldn't houses' underground pipes, which direct roof runoff under the verge to the gutter, be replaced by leaky pipes? That way, when it rained the water would drip through the holes and infiltrate to water the soil. Heavy rainfall (when it fell) could continue on its way to the kerb and gutter.

And that's what Chippendale residents have built. They now have leaky drains along their streets and these are doing a great job! It's a very efficient system. The water level is kept below ground, there's no evaporation due to wind or sunlight, and it's particularly useful for road verges where the topsoil is compressed by foot traffic and water falling just runs off.

The video below shows just how simple it is to build and install a leaky drain!