When winterizing underground water lines with a small compressor, be sure you blow out the each station area several times.
Always let the air compressors build up to full pressure when blowing out each line. Stop when the air pressure drops below 40 psi to let the air pressure build back up to full pressure.
It’s good to watch the farthest outlet of a line you are blowing out to be sure only a fine mist is coming out in the first seconds of blowing out the line. Once the pressure drops below 60 psi you will not get much water out of the line.