The death toll in Oman remained at 49 on Sunday, with the state-run Oman News Agency reporting that 27 remained missing. Another 12 people were killed when the storm moved on to Iran.
Aid began flowing into the capital, Muscat, and the hard-hit eastern provinces, which bore the brunt of the flooding and damage. Flights resumed Saturday into Muscat's Seeb International Airport, Oman state-run TV reported Sunday.
The water shortages stemmed from damage to two key water desalination plants.
The government's Cabinet of Ministers was meeting to estimate the cost of the extensive damage to the country's economy and infrastructure, and the cost of recovery.
The storm left wide swathes of Muscat under water, with floodwaters racing out of the mountains behind the city and demolishing homes and roads and sweeping away cars and buses.
Electricity was restored to some parts of the country, state-owned Oman TV reported Sunday, but it did not name those regions still experiencing shortages.
Muscat and the eastern city of Sur were hit by severe water shortages amid the country's usual high heat and humidity.
Residents scoured supermarkets for bottled water and siphoned drinking water from swimming pools, and the city government sent tanker trucks to try and cope, the Oman Daily Observer newspaper reported. Scuffles were reported at some of the 10 water distribution points set up by authorities in the aftermath of the disaster.
Muscat's residents have been paying $120 to $150 to get water delivered to their homes. The service was set up by independent companies before Gonu hit on Wednesday, and has continued at the same price after the disaster.
The shortages appeared to stem from damaged water supply pipes and damage to the Gubrah power and desalination plant, which normally supplies Muscat's 631,000 people with water.
Seif al-Shadidi, an official at the ministry of housing, electricity and water, said that water supplies would return to normal within two to five days, after flooded storage tanks at desalination plants are emptied of water and become fully operational again.
Another desalination plant north of the capital also closed because of damage to its pumping, Mohammed al Nabhani, the country's director-general for water resources told the Observer, Oman's English language newspaper.
The U.S. Navy contacted Oman, a U.S. ally, to offer help and loaded relief supplies and rescue personnel onto two ships in the Gulf, said Lt. John Gay.
But Oman had yet to request U.S. support, the Navy said. The U.N. humanitarian agency said it also had received no request for help.