The paper focuses on experimental investigation of the influence of outlet network volume and type on the course of surge in a single-stage low-speed centrifugal compressor. The test rig design is based on a 330 mm impeller (tip Mach number of 0.33) coupled with a vaneless diffuser and a scroll. During the measurements, the rig has been successively connected to a four meter long pipe and to an 11.8 m deep well. Time-averaged probing of pressures and temperatures has served to obtain the performance maps with both networks at three different positions of inlet guide vanes. Timeresolved measurements of static pressure were done in three chosen locations of the rig and enabled to trace the formation of flow instabilities at low flow rates. The analysis of received dataset revealed a reasonable impact of network design on the inception moment, quantitative and qualitative traits of deep surge. The most significant changes concerned the frequencies of the first surge harmonics and the nature of the process. ''Pipeline-surge'' reminded more of a standing wave whereas ''plenum-surge''-of a periodic process similar to the ones reported in the referenced studies.