My tank is only 26 gallons, but often when I have a small job to do, I don't even have to switch the compressor on. The air in the tank gives me a few minutes of use of a blow gun or air drill.

I did remove the cheap-o drain valve, replacing it with a 90-degree fitting, short piece of pipe, and a ball valve. That makes it very convenient to drain the water. If you own a compressor, don't forget this step. On any day when you run the compressor, drain the water.