Discovering new sources of high-energy gamma rays, both of galactic and extragalactic origin, is crucial for astroparticle physics. Currently, the HAWC and LHAASO observatories in the Northern Hemisphere use water Cherenkov detectors to continuously monitor secondary particles from atmospheric showers initiated by gamma rays. The Southern Hemisphere, however, lacks an equivalent experiment, limiting sky coverage in the detection of these sources. The future SWGO gamma-ray observatory, proposed to be located in the Atacama Astronomical Park in the Southern Andes of Chile, aims to fill this gap, providing continuous operation and a wide field of view, allowing for more comprehensive monitoring of high-energy gamma rays. To identify gamma-ray sources, it is essential to reconstruct the energy, direction, and type of primary particles that generate atmospheric showers. A gamma/hadron separator allows for differentiation between gamma rays, considered as signal, and hadrons, considered as noise. This differentiation is key to reducing background noise and improving precision in identifying gamma-ray sources. This research proposes a new gamma/hadron separation variable based on the arrival time distribution of secondary particles reaching the SWGO water tank array. For this purpose, the CORSIKA software was used to simulate atmospheric showers under suitable geomagnetic conditions. These preliminary simulations considered primary photons and protons with only vertical trajectories at the center of the array and a subset of energies ranging from 1 to 100 TeV. No detector efficiency, nor temporal, angular or energy resolution were included in the simulation. Considering these limitations, the optimal separation parameter found is the time corresponding to the 15th percentile of particles arriving within a ring of 100 to 150 m. The preliminary results obtained show a signal recognition of over 88% and background rejection of over 90%, laying the groundwork for future improvements and optimizations in the SWGO design.