This article is focused on Methods of Computation of Conveyance loss. Generally methods are two types like as inflow method and outflow method. It is a very simple method that involves measuring the number of water entering a reach and the number of water going out of that reach. The difference gives how much water lost. Discharge can be measured by using flume, weir or recent meter and allowance should be made for rain and evaporation. The accuracy on the method increases with the difference between the number of inflow and output rates.