Similar in typology to the other cisterns, but much smaller in size, with external axes measuring 4.50 metres by 2.72 metres, the thickness of its walls is 0.66 cms and its interior is covered by an “opus signinum” identical to that of Cistern Nº 1, preserved in very good condition. It has a half-round hydraulic cordon at the ground joints. Its depth is almost 2 metres and it is estimated that it can store about 8,000 litres of water.
The peculiarity of this cistern is that, probably in the time of Juan Vegazo, it was provided with a perimeter wall and a roof with a false dome, all built with reused stones and bricks, joined with a mortar very similar to the one used in Vegazo’s House.

Ground Plan



It was also provided with an access door with a lintel built with a slab, which has allowed it to be used as a watering place for cattle.
At the junction of the modern wall with the Roman wall, there are a series of small, quadrangular 20cm by 20cm putlog holes, which may have served as access to the bottom for cleaning.  It is estimated that it must have had some kind of relationship with the Thermal Baths building, located a few metres away and overlooking it in height, so it could have been a deposit external to the Thermal Baths.