Not too long ago I spoke how airlines could make it rain by flying through the clouds. A second way is to dump a Boeing 747 full of water to the ground below.
The first Supertanker was a Boeing 747-200 (see in the video above – N470EV) that was been modified to fight fires. Currently Evergreen uses a Boeing 747-100 (N479EV). It can hold 24,000 gallons of water or fire retardant. The Supertanker fought its first fire in the US on August 31, 2009 at the Oak Glen Fire. The aircraft is housed at McClellan Field outside of Sacramento, CA and is ready to go at any time.
If you want more, check this 7-min video on the Evergreen Boeing 747 Super Tanker.