Manually collecting a series of sequential, discrete water samples from soil water percolation samplers, or similar devices, that withdraw water from unsaturated porous media under continuous vacuum is a logistical challenge, though the resulting collection can provide valuable information on the dynamics present in both laboratory and field studies. This paper describes a sequential tension autosampler (STAS) that executes such sampling automatically. The STAS operates on 12 VDC and can be adapted for laboratory and field applications. A data logger was programmed to operate a series of solenoid valves, which direct soil water collected under tension to seven individual collection bottles. The number of sequential samples, sample period, start time, and between-sample interval are specified by the user. The operator only need to attend the system periodically to transfer water samples to storage vials and program the next sampling sequence. In a laboratory study, the apparatus successfully collected samples overnight or over several days.