In August of 1921, during a timber sketching flight in the Sioux Lookout District, Lieut. R. N. "Reg" Johnston spotted a forest fire on an island in Cliff Lake. He returned to base where he picked up a ranger equipped with the necessary fire-fighting tools. The ranger managed to extinguish the fire before it got out of control. It is believed that this was the first case in Ontario of an aircraft being used to suppress a fire.

Carl Crossley in 1944 began experiments dropping water on fires from aircraft. He decided that it would be useful as it took time to transport fire fighters to the scene of a fire. He installed a 45 gallon tank in the front cockpit of his KR-34 aircraft. He later converted a Norseman aircraft for waterbombing, using the floats to carry water. The water however, dispersed significantly while falling through the air, causing it to have little effect on fires.

The Ontario Provincial Air Service decided to use a simpler system. They dropped water filled wax paper bags through a cargo hatch in the Beaver. Unfortunately this system was not very effective. It was difficult to deliver a concentrated load of water and in addition to that, if a bag scored a direct hit on a fire, the force of the impact sent embers flying and spread them, worsening the situation!

Tom Cooke was a pilot in the employ of O.P.A.S. during the 1950's. He designed a water dropping design known as roll tanks. These tanks were mounted on the floats of Beavers and Otters. There was a forward facing pipe below the waterline which led the water up to the top of the tanks which were open. The pilot taxied for a short period of time, filling the tanks, then took off. This method was very effective in northern Ontario where there are many lakes. This allowed the pilot to make many water drops in a short period of time.

The roll tanks were a vast improvement over earlier methods of fire fighting, although they did have their drawbacks. They made onloading and offloading of cargo difficult, had a limited carrying capacity and produced a lot of drag. Further development of aerial waterbombing design led back to the carrying of water directly in the pontoons. This is the current method used in Ontario by the Ministry of Natural Resources Aviation Branch (formerly O.P.A.S.).

In addition to specially built pontoons, there are now planes that have been specifically built for water bombing. Canadair has two aircraft types for this purpose. The CL-215 is used by the Ministry of Natural Resources in Ontario. The CL-415 is similar to the 215, but has turboprop engines.