Why should you regularly drain the air tanks?

Question

Compressed air usually contains a certain amount of moisture and compressor oil, which can build up in the air storage tanks and damage the brake system. The tanks should be drained to clean out these accumulations. On a tank with a manual drain valve, draining should be performed at the end of each day of driving.

Accepted Answer

Because compressed air contains some water and the water collects in the tanks

Answer

Because the air gets old and needs to be replaced

Answer

To allow for a change in pressure