The Superbarrel Solution

As an engineer with the Metropolitan Water Reclamation District of Greater Chicago, John Chang is always on the lookout for ways to save water. Recently, while he was touring a manufacturing plant, some giant cube-shaped plastic containers caught his eye. It turned out the barrels were used to ship chemicals. Once they were empty, nobody knew what to do with them. If the barrels could be cleaned out, Chang wondered, could they be used to store some of the rainwater that otherwise flushes down Chicago's storm drains?

Chang put the manufacturing company in touch with Steve Wise, director of the natural resources program at the Center for Neighborhood Technology. The Chicago-based think tank is something of an R&D shop for testing new ideas in urban sustainability. When Wise looked at the huge white cubes, he imagined them as backyard rain barrels on steroids--he called them "superbarrels." Wise had one hooked up to the downspout of a Chicago affordable housing complex to catch runoff from the multifamily building's roof.

Wise's experiment is a simple test of an old adage: size matters. It also represents something of a challenge to a key premise of grassroots environmentalism. Small eco-conscious gestures, we are often told, add up to a big help for the planet. Following that advice, municipal governments, water districts and utilities across the country have offered customers subsidies for buying rain barrels, in hopes of relieving pressures on urban water supplies and sending less polluted runoff into waterways.

Yet the standard household rain barrel holds only 55 gallons--perhaps enough to water the flowers but not enough, even collectively, to make a big dent in urban water problems. By contrast, the superbarrel holds up to 330 gallons. Its colossal dimensions (40 by 50 by 54 inches) carry the potential to change the dimensions of water policy, too.

As Wise explains, normal rain barrels can handle only a fraction of the water associated with even a moderate rainfall. An inch of rain, fallen on a 1,000 square-foot roof, produces about 600 gallons of runoff. Conventional barrels harvest less than one-tenth of that volume. The superbarrel holds more than half.

Of course, the superbarrel presents its own problems. It's one thing to collect 330 gallons of water. It's another thing to use it all up, leaving the barrel empty for the next time it rains. Ideally, harvested water is used on gardens and lawns. But communities best suited for the barrels are often in urban settings surrounded by impermeable surfaces. Without a natural outlet for the harvested rainwater, people may resort to emptying their barrels into the street.

Wise says that problem can be overcome. He proposes turning useless swaths of pavement into neighborhood rain gardens and planter boxes. But even if that isn't possible, he says, there's an environmental benefit to holding rainwater for a time and releasing it later. Major downpours can quickly overwhelm stormwater systems, which in some cities can cause sewage releases. "Just dribbling the water back out into storm drains more slowly," Wise says, "is a benefit to public infrastructure."