Abstract: Slugs of high pressure air at pressures of about 2000 psi (150 atmosphere) are jetted against the screen of the casing or well wall in the aquifer of a water well. Fine material washed from the aquifer by this procedure is picked up from the bottom of the well by an airlift pump. The development of a new well will remove the mud cake from the bore and, also, rearrange fines and silt that were in the aquifer before drilling. On old cased wells, the procedure will remove algae and rust from the screen of the casing, rearrange the gravel pack around the screen and, remove silt and fines that have gathered within and around the gravel pack.