The most reliable method used to estimate deep percolation is using Lysimeter which proves to be expensive and time consuming as well. In this study, deep percolation has been estimated by using water balance method. The experimental setup consisted of two lysimeters in the Hydraulic Engineering field lab, I.I.T., Roorkee in which maize crop was grown. Regular measurements of soil moisture were made at the depths 0-20 cm, 20-40 cm, 40- 60 cm, 60-80 cm and 80-100 cm using gravimetric method. The evapotranspiration estimates were determined using Penman-Moneith equation. The deep percolation is calculated using the water-balance approach. The deep percolation calculated using the water-balance approach is comparable to the observed values of deep percolation which are obtained from the lysimeters.