The city of New Orleans ranks third in the U.S. when it comes to rainfall, and drainage has always been an issue. It doesn't help that parts of the city are several feet below sea level and surrounded by water, which makes it susceptible to flooding.

A landscaper in New Orleans named Dan Johnson, who calls himself Greenman Dan, came up with a solution last year that harnesses the excessive rainwater for household use.

His water-harvesting system captures the rain and stores it in underground tanks.

Each building has its own tank, which can store anywhere between 500 and 50,000 gallons of water. The water can be used after the rainfall for irrigation, washing cars, filling up a swimming pool or other household uses.

Eight systems have been installed in the last year. Several have been incorporated into properties built by Project Home Again, a nonprofit that has given away 101 houses to families whose homes were destroyed by Hurricane Katrina.

Johnson said the combined capacity of the installed systems can hold enough rainwater to keep over a million gallons a year out of the storm drains.

"We are making a dent," he said.