Efficient water management requires accurate estimation of evapotranspiration. A study in Sri Lanka used a simple technology to estimate evapotranspiration. They compared measurements from a lysimeter with estimations from different methods. The lysimeter overestimated evapotranspiration in February, March, and April of 2008 compared to the Penman method. Recommendations were made for improving the accuracy of evapotranspiration estimations using lysimeters.