Abstract: Apparatus for recovering drilling mud and the like comprises a vacuum pump (12) applying vacuum to a vessel (10). A hose (14) and suction head (22) allow an operator to remove the mud into the vessel (10). When the vessel (10) is full, vacuum is cut off by ball valve (16). A pneumatic logic circuit (20) detects loss of vacuum and disables vacuum pump (12) for a predetermined time, allowing the contents of vessel (10) to be discharged via flap valve (18) (or by pumping--FIG. 3). Discharging is thus automatic, without operator intervention.