A clean beer keg is vital for the taste and quality of your beer. Cleaning your beer keg can take 30 to 60 minutes and should be done before it is refilled. The reason for this is because a even couple of teaspoons of leftover beer can mildew and ruin an entire keg. Trust me when I tell you the hour spent cleaning a keg is much easier than filling it and realizing you ruined your new batch and have to dump it, clean it then refill it.
Here is what you will need before you begin:
Acidic solution for sanitizing (specially made for kegs)
A wrench (7/8")
You will use your wrench to remove the posts, which are located on the top of the keg. This will allow you to access the inside of your keg.
Rinse your keg out with water. The easiest way to do this is outside with a garden hose, since you are going to be using a lot of water. This will remove anything that may have accumulated inside the keg and get rid of any remaining beer.
Wash your keg with the cleansing powder. To make your cleansing solution, mix 2 ounces of powder with one gallon of water. This can be done inside the keg. Place the lid on the keg (without the posts), hold the keg together and shake it thoroughly. It is a good idea to periodically hold the keg upside down for a half an hour to remove everything from the inside of the top of the keg.
Clean the posts. When you dump the solution from your keg, pour some into a bowl and set the posts inside to clean them.
Thoroughly rinse the keg. This will need to be done numerous times with both the keg and the posts. You will be done only when you can no longer smell any chemicals inside the keg.
Sanitize your keg. Pour a gallon of the acidic liquid sanitizer solution into the keg. This is a non-rinse solution, since you are going to force it out through the tap after the keg is put back together.
Reassemble your keg thoroughly. This will require reattaching the posts and hooking the keg up to the CO2.
Remove the sanitizer by forcing it from the keg with the CO2.