How does one clean a furnace air filter?

There are 5 main steps in cleaning a furnace air filter which you must follow. The first thing to do is turn off the power of the furnace. Next, you must locate the air filter as you may have to unscrew some panels. Thirdly, you must remove the dirtied air filter by sliding it out of the housing. After this, you have to wash the filter with a hose until the water going through it comes out clear and leave it to dry. Finally you must slide it back into the furnace and turn it on.