Pulsed discharges in water are investigated to obtain knowledge of fundamental aspects of their behavior. The electrical energy dissipated in one pulse is measured with a calorimetric method to be 80 mJ. From photographs detailed information on streamer structure is obtained. In a gap of 20 mm at a pulse voltage of 20 kV the average length of the streamer in tap water is 5 mm, in deionized water it is 11 mm. The number of streamers is higher in tap water. The propagation velocity of the streamers is determined using photomultipliers and is in the order of 106 m/s.