Water supply and sanitation in Gibraltar have been major concerns for its inhabitants throughout its history. There are no rivers, streams, or large bodies of water on the peninsula. Gibraltar's water supply was formerly provided by a combination of an aqueduct, wells, and the use of cisterns, barrels and earthenware pots to capture rainwater. This became increasingly inadequate as Gibraltar's population grew in the 18th and 19th centuries and lethal diseases such as cholera and yellow fever began to spread. In the late 19th century, a Sanitary Commission instigated major improvements which saw the introduction of large-scale desalination and the use of giant water catchments covering over 2.5 million square feet (nearly 250,000 m2). Today Gibraltar's supply of drinking water comes entirely from desalination, with a separate supply of saltwater for sanitary purposes. Both supplies are delivered from huge underground reservoirs excavated under the Rock of Gibraltar.