But the aqueduct, and others built in modern times, are running so dry that small hotels and guesthouses in the city and nearby coast are being forced to turn tourists away. They don't have enough water to guarantee their guests a toilet that flushes or a shower after a day out in the summer heat.

Sicily began enforcing water restrictions in February when the region declared a state of emergency amid a relentless drought. Leaky, aging infrastructure has only worsened the shortages, which have hit tourism and agriculture alike, two sectors crucial to Sicily's economy.

Rationing is in place for more than 1 million people across 93 communities. Some are having to reduce water consumption by up to 45%. That means taps run dry according to schedule, and supply is shut off completely overnight in most places. Having enough water to drink is a matter of getting organized during the day.

On TripAdvisor and other travel forums, tourists are asking whether it's worth visiting Sicily's impacted areas. Hotels are warning clients about potential shortages, and are helping visitors rebook elsewhere on the island where restrictions are less severe or not in effect.

At the Le Cinque Novelle bed and breakfast (B&B) in central Agrigento, where restrictions are tight, the owners have put filters on their showers and sinks to save as much water as possible. But their guests often complain.

"Rightly, people ask us for reassurances before coming, but we don't know what to say," Giovanni Lopez, who owns the B&B, told CNN. "The situation is quickly impacting the entire tourist accommodation sector, which risks serious economic consequences, given that tourism is a sector almost everyone in this part of Sicily relies on."