Sloshing in outdoor-pools in high-rise buildings under earthquakes poses significant structural risks as seen from recent earthquakes in Bangkok, Thailand (2025) and Taipei, Taiwan (2024). Overflowing water can impact surrounding interior-walls and run off onto the surrounding streets, leading to damage and life safety issues[1][2][3]. In this research, the overflow of a water pool on a building under constant and random(earthquake) excitations is investigated coupling fluid flow with the building's dynamic response in a weakly coupled fluid-structure interaction setting. The behavior of the water is simulated using the MPS method(ParticleWorks), the building as a lumped mass MDOFsystem (OpenSEES), and the fluid motion is coupled to the building through the rigid body pool(Fig.1). The effect of the earthquake, building fundamental frequency, pool-size, and poolside length on the total water overflow discharge volume from the pool as well as the maximum applied force on the interior-walls surrounding the pool is investigated. The method is applied to a pool located atop a 30-DOF building(Fig.1). Results under constant amplitude excitation show that pool-side length strongly affects overflow rates and peak wall forces, with longer sides mitigating abrupt impacts(Fig.2,Fig.3). Excitation frequency effects were also notable, with pronounced amplification near resonance. Trends similar to the constant amplitude excitation are observed under earthquake excitation, where forces decrease with an increase in pool side lengths as well as increase when the length of the pool results in a water oscillation frequency resonating with the buildings fundamental frequency. One sees that the fluid-structure coupled model in this study enables identification of critical response for risk evaluation and structural design.