Ground water has emerged as an important source to meet the water requirements of various sectors including the major consumers of water like irrigation, domestic and industries. The sustainable development of ground water resource requires precise quantitative assessment based on reasonably valid scientific principles. The Ground Water Estimation Committee- 1984 till now formed the basis of ground water assessment in the country. The ground water development programme implemented in the country was also guided by ground water resource availability worked out from this methodology. The experience gained in last more than one decade of employing this methodology supplemented by number of research and pilot project studies has brought to focus the need to update this methodology of ground water resource assessment. The National Water Policy also enunciates periodic assessment of ground water potential on scientific basis. The Ministry of Water Resources, Govt. of India, therefore, constituted a committee consisting of experts in the field of ground water to recommend a revised methodology. This report is the final outcome of the recommendations of the committee.