This is a Roman reservoir for water distribution that was already in use in the first century. Its entrance and exit aqueducts are also present. The pool is rectangular in shape and measures 15.30 m x 12.30 m, and is 1.35 m in depth, supporting a significant volume of water: more than 250,000 liters. The walls are made of rock and limestone, two of which are built against the ground and the other two are supported by buttresses. In the interior, the pool is plastered with limestone mortar and red colored blended ceramic (opus signinum mortar).
In the structure’s interior joints, there are remains of some support beams which were meant to seal the reservoir, a common technique in Roman liquid containers, which can also be seen in their salting tanks. Next to the walls, a draining system can be found in addition to a stairway foundation, which provided access for cleaning the pool. The water conduit that deposited into the reservoir was positioned in the northeast corner, while the exit conduit lies on the southwest side and supplied water to the villages in the El Alamillo area and possibly to El Rihuete.
The water came from a spring, which is dry today, located a few kilometers from the pool in the neighboring area of Las Balsicas. Some sections of the aqueduct bringing water to the reservoir can still be located. The aqueduct was built using similar techniques to those used for the reservoir. The canal measured 0.2 meters wide and its route was adapted to the land’s features of the Sierra del Algarrobo foothills.