External loading such as flooding and tailings emplacement can potentially influence deep groundwater pressure. However, the current groundwater numerical models such as MODLFOW cannot simulate these effects. In this study, a new MODFLOW package was developed to simulate the impact of external loading on groundwater levels. In doing so, the current subsidence and aquifer compaction package (SWT) was modified and a new component was added to the geostatic equation to account for the external load. The SWT package uses updated geostatic stress and hydraulic pressure to estimate effective stress. Upon the calculation of effective stress, skeletal storage and compaction changes were calculated and changes in groundwater storage were translated into flow and added to finite difference equations. Given that the loading impact decreases with increase in depth, two types of equations (i.e. linear and power) were also introduced in the package to simulate the loading dissipation. The new package was tested on an identical sample simulation to the one provided in the SWT package. A model run was undertaken with the presence of external load assuming flood waters of 0.1 m deep. The result shows that the groundwater levels increase by approximately 0.04 m in response to 0.1 m of flooding at the surface. The result also shows a depressurization response to the sudden removal load, before quickly recovering by the end of the stress periods. In the next step, the package will be tested in the real case scenarios. We also encourage others to test the package and investigate numerically the impact of external loading.