If you saw students hoofing wheelie bins of water from a roof, you’d probably write it off as another hilarious jape by the underemployed. But back in 1996 when Greg Yeoman, Mike Hannah, Brendan Poole and their co-conspirators were tipping bins, they weren’t targeting unsuspecting passersby. They were busy testing the EnviroPod, a storm-water drain filter they had invented.

Thirteen years on, the unsuspecting people of Auckland, Brisbane, Sydney and many other cities are unwittingly stepping over subterranean EnviroPods many times a day. Each EnviroPod uses a range of mesh screens to filter out pollutants like heavy metals—copper, zinc, cadmium and lead—oils, sediment and even asbestos. It requires no power and little maintenance.

The ingenious device has helped build Stormwater 360, Yeoman and Hannah’s firm, into a company with offices in New Zealand, New South Wales and Queensland. Over 7,000 EnviroPods remove up to 30 kilograms each of sediment, trash and debris every three months, and over 5,000 StormFilter media filter cartridges remove the finer sediments, organics and heavy metals from runoff.

Previously, storm water usually drained directly into rivers and harbours. “It’s been a lot of bloody hard work testing and verifying our products for the various councils around New Zealand and Australia,” says Yeoman. “The solutions are here, so it’s nice to see them being adopted proactively.”

In the early days, the trio could not afford to pay wages for three, so two worked while the third would shoestring it around Asia for six months, because it was cheaper than living in New Zealand.

By 2002 they were just about out of cash and did a joint venture deal with Industrial Galvanising. IG bought 53 percent and was effectively in charge, but the original team still provided the brains and direction. In 2007, Yeoman and Hannah managed to scrape together the money to buy their baby back.

Yeoman says Stormwater 360 still has a green heart pulsing within. “We’re all big into our fishing and surfing. Our water can become very polluted from road runoff. Becoming commercial, your objectives change, but to this day, cleaning that water is still our focus.”