Recently, rainwater has been used to meet the demand for uses other than human consumption. The artificial wetland—storage tank system built at the Pontificia Universidad Javeriana (PUJ) was built as an alternative source of irrigation for the local area. The system is made up of three components: a catchment system from the drainage pipelines coming from the parking structure, a sub-surface artificial wetland used for the water treatment, and a storage and distribution system for irrigation. A hydraulic and hydrological assessment for the system, a water balance for the system's tributary areas, and a water demand analysis for the vegetative species at PUJ were carried-out to evaluate the system's performance. The results from this assessment demonstrated the presence of short-circuiting patterns that affected the wetland hydraulic performance. Furthermore, there were considerable differences between the inflow and the outflow, which suggests a non-optimal water transport inside of the wetland.