An air compressor is a great addition to any shop and with proper care will be a tool that will be a part of that shop for many years. Regular maintenance includes the obvious things like changing the compressor oil, but equally important to your compressor's life and performance is regular draining of the air tank.
Air contains water, and when allowed to cool in the compressor tank after being compressed some of this water returns to liquid and settles in the bottom of the tank. Over a period of time, which can sometimes be as short as a day, the level of the water builds up and can be mixed with the compressed air as it exits the tank on its way to your air-powered tool. Vertical tanks especially can have the air storage capacity reduced if this water is allowed to accumulate over time. This reduced capacity seriously impacts tool performance in a negative way.
The compressor should be drained after every use. Especially on humid days, compressors make a lot of water. Left in the tank this water does nothing but rust the tank; obviously the problem is made worse when the water is allowed to sit in the tank for extended periods of time.
