Water in Oman

Oman balances two water civilisations. One is the UNESCO-listed aflaj: thousands of gravity channels still watering mountain oases under centuries-old community law. The other is a modern coastal economy run on efficient desalination IWPs procured by Nama. Oman is the Gulf's quiet good example, with corporatised utilities, real if partial tariffs, high reuse ambitions and cyclone-tested resilience engineering.

The system runs the region's newest and oldest infrastructure at once. Nama PWP's procured desalination fleet supplies 86% of drinking water.³⁰ Meanwhile some 3,000 aflaj, gravity channels engineered over centuries, still irrigate the interior. UNESCO inscribed five of them as World Heritage in 2006.²⁸

A quick-reference dashboard for Oman: headline economy and water indicators⁴⁵⁴⁶, water stress against the scarcity thresholds, non-conventional supply, and the institutions behind the sector. The commercial picture, with buyers, deal structures and the project pipeline, is in the market brief.

One interactive map of Oman's water, built from real geodata. Climate & drought maps the aridity gradient (WorldClim) with warming projections. The WRI Aqueduct layers, covering overall water risk, water stress and flood risk (plus groundwater decline where the trend is significant), shade every river sub-basin by its 0–5 risk score. Demand shows where the population, and the water demand, concentrate. Infrastructure brings the physical system together: rivers, dams (FAO AQUASTAT), treatment plants, desalination and the major conveyors. Hover any sub-basin or marker for detail; sources are cited under each view.

Oman covers 309,500 km², with about 3,165 km of coast on the Gulf, the Sea of Oman and the Arabian Sea.¹ Musandam is an exclave, separated from the rest of the country by the UAE.²⁷ The Hajar mountains form a 700 km arc from Musandam and rise above 3,000 m at Jabal Shams.²¹ The Batinah plain covers about 4% of the land but holds over half of the farmland.²⁷ Desert, sand and gravel plains cover 82% of the country, including part of the Rub’ al Khali.²⁷

Winter rain in the north, monsoon in the south

The north and centre get their rain in winter, from November to April. Cold fronts bring Muscat about 75 mm and the Hajar up to 120 mm.²⁷ Dhofar in the south gets the June–September khareef, and Salalah typically receives about 131 mm a year.²⁷⁶ Rainfall ranges from less than 20 mm in the interior desert to over 300 mm in the mountains.²⁷ National estimates range from about 60 to 100 mm a year.²⁷¹ Most wadis flow for only hours or days after a storm.²⁷

Heat and cyclones

Annual mean temperatures run from 10 °C on mountain peaks to 26 °C across most of the country. In June the interior plains top 42 °C.² In June 2018 Quriyat recorded a 24-hour minimum of 42.6 °C.¹ Station records show warming of about 0.3 °C a decade since 1980, 1.4 °C in total, with rainfall falling at most stations.² Cyclones bring the extremes. Of 176 Arabian Sea cyclones in 76 years, 30 hit Oman directly.⁷ Gonu in 2007 caused 50 deaths with 900 mm of rain over two days, and Shaheen dropped 369 mm on Khabourah in October 2021.⁸ Cyclone losses between 2002 and 2021 came to about US$7.3 billion.¹

Projections

National assessments point to late-century warming of about 2–3 °C under high emissions. Rainfall in the near term could fall about 50 mm below the 2000–2020 baseline.¹ Heatwave days are projected to rise by 20–40% by 2050 under high emissions.¹ By 2100 daily maximum temperatures in Al Dhahira could peak at 52 °C.² Coastal sea temperatures are projected to rise by an average of 1.76 °C by the 2040s, which hurts desalination efficiency.² Model ensembles disagree on rain: the World Bank’s multi-model median is wetter by late century.³

Rainfall and temperature in numbers

Averaged over the whole of Oman, ERA5 reanalysis gives about 48 mm of rain a year and a mean temperature of 27.9 °C for 1991–2020. About 40% of that rain falls in March, May and June, and 10 months average less than 5 mm. Since 1971 the country has warmed by about 0.24 °C a decade. At such low totals, percentage changes in rainfall between decades mean little in absolute terms.

Projected change

Source: World Bank Climate Change Knowledge Portal, retrieved September 2026. ERA5 0.25° reanalysis for the annual series (1950–2022) and the monthly climatology (1991–2020); CMIP6 0.25° multi-model ensemble median for the projections, as change against 1995–2014. These are national averages, which hide the gap between wet highlands and dry interiors, and reanalysis rainfall over deserts carries wide uncertainty.

Oman’s renewable water is about 1,300 million m³ a year, and the national deficit is 316 million m³.²⁹ In 2017, 79% of the rain that fell evaporated.² Fresh groundwater lies mainly in the far north and far south, where rain and recharge occur. Elsewhere it is mostly brackish to saline.²⁷ The largest aquifer stores are Masarrat in Al Dhahirah, at 19,500 million m³, and the Sharqiyah Sands, at 12,000 million m³.² Cyclones matter for recharge: Mekunu in 2018 delivered about 3.2 km³ of net recharge to the Najd basin in Dhofar.⁴ Desalination supplied about 455 million m³ in 2025 and now carries the cities.³²

Oman withdrew 1,321 million m³ of water in 2003. Agriculture took 88.4%, municipal use 10.1% and industry 1.5%.²⁷ Groundwater depletion was then estimated at about 134 million m³ a year, and coastal over-pumping had drawn in seawater.²⁷ Renewable freshwater is no more than 296 m³ per person a year.³⁰ The government reserves the fossil aquifers of Dhofar, Al Dahra and Sharqia for urban supply and future needs.²⁷

Farms and the aflaj

Equipped irrigated land grew from about 28,000 ha in the 1970s to 61,550 ha in 1993, 57% of it on the Batinah coast.²⁷ All farming is irrigated, all of it from groundwater through wells and aflaj. Date palms cover almost half of the harvested area, and Oman has more than 8 million of them.²⁷ Wells supply 67% of groundwater withdrawal and aflaj 33%.²⁷ The 1997 national inventory counted 3,017 working aflaj irrigating 21,606 ha.²⁷ UNESCO lists falling water tables as a threat to them.²⁸

Law followed the pumps. A 1988 royal decree declared water a national resource, and a 2000 decree regulated wells and aflaj.²⁷ In September 2026, 49 contracts worth RO 1.19 million were signed to restore 64 aflaj in North Batinah damaged by a low-pressure weather system.³⁴

Dams for recharge

Oman began building recharge dams in 1985 and had 31 by 2006.²⁷ By July 2026 it had 212 dams with 458.79 million m³ of storage. They include 53 groundwater recharge dams holding 108.6 million m³.³³ Wadi Dayqah, the largest, holds 100 million m³, and 33 more dams are planned.³³

The shift to the sea

Desalination output rose from 34 million m³ in 1995 to about 109 million m³ in 2006.²⁷ In 2025, 92 main plants produced 455.36 million m³.³² Desalination now meets 86% of drinking-water needs but only 31% of total water demand.³⁰ Peak demand in the main northern system is forecast to rise from 1,211,000 m³ a day in 2025 to about 1,483,000 m³ by 2032. The 300,000 m³/day Ghubrah III plant is due in 2027.³⁵ Reuse is growing too, with 119.5 million m³ of treated wastewater produced by 67 main plants in 2025.³²

Withdrawals over time

FAO’s AQUASTAT estimates put Oman’s freshwater withdrawals at 1,197 million m³ in 1991 and 1,634 million m³ in 2022. Agriculture’s share of the total moved from 93% in 1994 to 81% in 2022.

Source: FAO AQUASTAT via the World Bank World Development Indicators, retrieved September 2026. AQUASTAT revises national figures irregularly and fills the years between surveys, so a jump between two adjacent years usually marks a new national estimate rather than a change on the ground.

Oman’s dam count has climbed fast, from 155 in 2018 to 212 by July 2026.²³³ The largest, Wadi Dayqah near Quriyat, holds 100 million m³ behind a 75 m wall.¹⁰ Muscat opened two flood protection dams in February 2025, Wadi al Jifnain and Al Jufainah.¹¹¹² Four more dams worth RO243 million, financed by the Islamic Development Bank, include Wadi Majlash at 140 million m³.⁹ A treatment plant at Wadi Dayqah, contracted in 2025, will turn dam water into 35,000 m³ a day of drinking water and 30,000 m³ for irrigation.¹³

Desalination and transmission

Nama Power and Water Procurement is the single buyer of water capacity.⁵ Privately owned plants supply the main northern system: Barka IV at 281,000 m³/day, Sohar IV at 250,000, Qurayyat at 200,000 and Ghubrah II at 191,000.⁵ Ghubrah III, at 300,000 m³/day, is expected in February 2027. Salalah III has supplied Dhofar with 113,650 m³/day since 2021.⁵ About 90% of the 445 million m³ produced in 2025 was desalinated, on the water company’s figures.¹⁴ Pipelines carry that water inland. The 230 km Sohar–Dhahirah line opened in January 2023.¹⁵ By November 2025 Nama Water had completed more than 620 km of new mains and 27 reservoirs.¹⁶

Wastewater, networks and reform

Between 2021 and 2025 the number of treatment plants grew by 9%, and the wastewater treatment rate reached 98%.¹⁷ In July 2026 a consortium led by SUEZ won a 15-year, RO878 million performance contract for Muscat and Sharqiyah.¹⁸ Its area has 22 treatment plants, 10,700 km of water pipes and more than 400,000 smart meters. The contract aims to cut water losses there from 34% to 11% by 2040.¹⁸ An aquifer storage pilot began in 2026 to bank surplus desalinated water in the Sharqiyah Sands.¹⁴ In March 2026, 97 water and wastewater projects worth RO966 million were under way.¹⁷

The asset base in numbers

Sources: FAO AQUASTAT regional dam inventories (CC BY 4.0), which list large dams with a published capacity and can lag recent construction; the MENA Water Review major projects register, where each record cites its source on the project page. The database follows large contracted projects, not the whole asset base.

FAO called rising salinity probably the single most economically devastating water problem facing Oman.²⁷ Near the sea, Batinah well water can reach an electrical conductivity of 10 dS/m. Salinity has risen since farm expansion peaked in 1988, and productive farms have been abandoned.²⁷ Between 1984 and 2005 the Seeb–Suwaiq coast lost 2,714 ha of irrigable land to saltier water, and a saline front was reported 12 km inland at Barka.³⁶ A study of about 58,000 Batinah wells from 1990 to 2018 found salinity rising with urban growth and over-pumping.³⁷ At current pumping, a model projects very saline water moving 0.8 km further inland at Wadi Al-Jizi by 2040.³⁸

Soils are salting up as well. On eight Batinah farms, soil salinity rose from low to highly saline between 1993 and 2020.³⁹ Agrochemicals are a hazard because the groundwater is unconfined and the soils sandy.²⁷ At sea, a 2008–09 red tide shut several desalination plants in Oman and the UAE for up to two months.³⁰ In 2026 an oil spill from a damaged tanker threatened about 40 km of coast near Ras Madraka and Masirah Island.⁴²

The reported indicators

Sources: WHO/UNICEF Joint Monitoring Programme via the World Bank; SDG 6.3.1 and 6.3.2 from the UN Statistics Division SDG database, retrieved September 2026. Safely managed means an improved source on the premises, available when needed and free from priority contamination. SDG 6.3.2 rests on each country’s own monitoring network, so a high share can mean few water bodies were assessed, and values move when methods change between reporting rounds.

Oman has no transboundary river. Its shared waters are aquifers with the UAE, Saudi Arabia and Yemen, and none is covered by a water agreement.²⁹

The southern Umm er Radhuma–Dammam

This system covers 678,000 km², of which 249,000 km² lie in Oman.²⁹ It is used only in Oman’s Dhofar–Najd region and around Jebel Hafit in the UAE. Oman abstracts an average of 45 million m³ a year, the UAE 7.7 million m³.²⁹ Modern recharge in the Najd averages only about 12 million m³ a year.²⁹ Yet Najd groundwater use rose from about 19 million m³ a year in 1995 to about 139 million m³ in 2021.³¹ ESCWA flags Jebel Hafit and the Oman–Saudi–Yemen border area as priorities for joint management.²⁹

The Western Gravel Aquifer

Along the border around Al Ain and Buraimi, the Western Gravel Aquifer is recharged by about 30 million m³ a year. Its shared part stores 2.6 billion m³ of fresh and 18 billion m³ of brackish water.²⁹ Oman taps it in Al Dhahirah, mainly through aflaj.²⁹ Water levels have fallen by up to 50 m west of Al Ain, and efforts to launch joint management have produced no concrete results.²⁹

The 2026 war

The war reached Oman’s coast. On 11 March 2026 Iranian drones struck oil storage at the Port of Salalah, one of the country’s main ports.⁴⁰ A tanker damaged off Yemen in June later ran aground and leaked oil off Oman.⁴¹

The record

Joint bodies

• Donaukommission (Danube Commission) (DCXX)Danue · 1948 · Austria, Bulgaria, Croatia, Germany, Hungary, Moldova, Russia, Romania, Serbia, Slovakia, Ukraine
• International Commission for the Protection of the Danube River (ICPD)Danube · 1994 · Austria, Bosnia Herzegovina, Bulgaria, Croatia, Czech Republic, Germany, Hungary, Moldova, Montenegro, Romania, Serbia, Slovakia, Slovenia, Ukraine, EC

Source: the river basin organisation database of the Transboundary Freshwater Dispute Database (2013). A joint body on paper is not evidence that it meets.

Shared aquifers

• Dacian BasinRomania, Serbia · data limited
• Danube-PrutRepublic of Moldova, Romania, Ukraine · data limited
• Dobrudja / Dobrogea Neogene Sarmatian aquiferBulgaria, Romania · data good
• Dobrudja / Dobrogea Upper Jurassic - Lower Cretaceous AquiferBulgaria, Romania · data good
• Körös Valley, Sárrét, Shallow Crişuri aquiferHungary, Romania · data moderate
• Körös – Crişuri holocene, pleistocene transboundary aquifer (Hortobágy-Nagykunság Bihar Northern Part)Hungary, Romania · data moderate
• Middle Sarmantian Pontian AquiferRepublic of Moldova, Romania · data good
• Miroc & GolubacRomania, Serbia · data limited
• Mures / Maros alluvial fan aquiferHungary, Romania · data good
• Nyírség, keleti rész / Nyírség, east margin aquiferHungary, Romania · data moderate
• PrutRepublic of Moldova, Romania · data limited
• SiretRomania, Ukraine · data limited
• Somes / Szamos alluvial fan aquiferHungary, Romania · data good
• Umm er Radhuma-Dammam Aquifer System (South): Rub' al KhaliSaudi Arabia, UAE, Yemen · data moderate
• Upper Pannonian-Lower Pleistocene / Vojvodina / Duna-Tisza köze déli r.Hungary, Romania, Serbia · data good

Source: IGRAC and UNESCO, Transboundary Aquifers of the World. Data reliability is IGRAC’s own assessment of the information behind each outline.

Oman restructured its water sector in 2020. A royal decree in August renamed the agriculture ministry as the Ministry of Agriculture, Fisheries and Water Resources and moved the water resources divisions to it.²³ Another renamed the electricity regulator as the Authority for Public Services Regulation.²⁴ In December a third decree gave the ministry water policy and the regulator oversight of water and wastewater. It also folded the Public Authority for Water into the wastewater company, with Dhofar served separately.²⁵ By 2022 the merged company was part of the Nama group.¹⁹

Law and tariffs

The Water Resources Protection Law of 2000 requires a ministry licence for any change to a falaj channel, and well licences carry fees.²⁶ A 1988 decree bars new wells within 3.5 km of a falaj mother well.²⁷ A sector law of June 2023 lets the regulator set network standards and, with cabinet approval, open the market.²⁰ Tariffs moved toward cost from 2021. Citizens pay 2.5 baisa a gallon for up to two accounts, other residents 3 baisa and non-residential users 4.5 baisa.²¹ In 2024 the regulator cut water connection fees by 70%.²² The National Water Sector Master Plan runs from 2015 to 2040.²

Oman’s path is continuity with more ambition. Desalination carries the cities, so the main risks sit offshore: warmer seawater, algal blooms and, in 2026, drone strikes and oil spills along the coast.^2304041 New dams, the Wadi Dayqah treatment plant and aquifer banking in the Sharqiyah Sands are the hedges.⁹¹³¹⁴

Inland, the problems are older. The national water deficit persists, the Batinah’s salt front is projected to keep advancing, and summers are getting hotter.⁹³⁸¹ The aflaj carry a lesson the region keeps relearning: institutions outlast pumps.