This paper presents an experimental investigation of a submerged round jet discharging vertically into a deep well. The research work was concentrated on two positions of the jet: (a) impingement at the centre of the well; and (b) impingement near the upstream side of the well, Square and rectangular shaped wells were tested for various pipe heights and well dimensions. Using a laser Doppler anemometer, velocity distributions were measured in the vertical and horizontal planes inside the well and compared with those for the free jet and the wall jet, The flow pattern and velocity decay of the jet were studied while varying the ratios of well height to pipe diameter between the practical limits of 6 to 16, Based on these results, an optimum size for a deep well has been indicated, with satisfactory prototype performance.