The tank at the head of the small road from Pumsaint to Caio was thought to be modern since it still holds water. However, when the level of the water was low in 1970, it yielded large quantities of Roman pottery which show that it is of Roman origin and built early during their exploitation of the mines. The section shows that it was connected to a smaller tank just below the modern road by a drystone culvert in a cascade. The lower tank also holds water but is in an advanced state of eutrophication. The collection of fragments included Samian ware and coarse ware from over 100 separate pots, and must have fallen into the reservoir when the mines were in full operation. Analysis of the pottery fragments showed a distribution of ages from the late 1st century AD through to the end of the 4th century. Since the fort and fortlet under the present village of Pumsaint ends in the middle of the 2nd century, it shows that mining continued for a long time after the military evacuation.