The catchments are no longer used. Today, Gibraltar's main supply of water is from distillation plants at sea level, although water is still stored inside the Rock.
Water Catchments
The most unique source of water was catchments on the east side of the Rock covering 34 hectares. Massive sand slopes were covered by sheets of corrugated iron at the beginning of the 20th century. The rain falling onto the sheets was then channeled into the Rock, where reservoirs capable of holding 16 million gallons were excavated.