Effective irrigation water management beginswith timing and regulating irrigation water application in a way that will satisfy the need of the crop without wastingwater, soil and crop nutrients. This involves supplying water according to the crop requirement, quantity that canbe held by the soil and is available to the crop at rates tolerated according to the soil characteristics . So measuring water in fields is very essential step in irrigation management systems. Thereare many water flow measurement techniques as well as different types of water flow me ters used in irrigation to measure the volume of water flow in pipelines but these all are too costly. This paper describes design and development of low cost automatic water flow meter which supplies only required amount of water to the crops saving water as well as energy. G1/2 Hall Effect water flow sensor is usedas a sensing unit with a turbine rotor inside it whosespeed of rotation changes with the different rate of flowof water. The Hall Effect sensor outputs the corresponding pulse train for frequency input to the microcontroller. The whole system comprises of AT89S52 microcontroller, G1/2 Hall Effect water flow sensor , relay, optocoupler, a water pump, 5V supply, LCD, keypad and some passive components. The AT89S52 microcontroller is programmedin Keil development Tool.