Water in Oman

Most of Oman’s wadis flow for only hours or days after a storm, and its fresh groundwater lies mainly in the far north and far south.¹ Farming, all of it irrigated from groundwater through wells and aflajFalaj (plural aflaj) A traditional irrigation system in which water is channelled by gravity from underground sources or springs to support agriculture and domestic use. UNESCO counts some 3,000 still in use in Oman. Source: Aflaj Irrigation Systems of Oman, UNESCO World Heritage Centre, accounts for most of the water withdrawn.¹ Desalinated seawater now supplies most of the public water, bought from private plants by a single buyer, Nama Power and Water Procurement.^2 3 Along the coast, over-pumping has drawn seawater into the aquifers.¹

In Oman’s oases, water has long been shared by the clock. The aflaj carry it by gravity from underground sources or springs to farms and homes.⁴ Some are very old. At Salut, in the western foothills of the Hajar mountainsHajar Mountains A high, rugged range in northern Oman that runs south-east, parallel to the Gulf of Oman coast, from the Musandam Peninsula to near Cape al-Hadd. Its highest point, Mount Shams, reaches 2,980 m. Source: Oman: Land, Encyclopaedia Britannica, lime deposits inside a falaj gallery show that water was flowing through it by at least the mid-5th century BC,⁵ and FAO estimates that many of the aflaj in use today are over a thousand years old.¹ Each community divides its falaj water by time, with the shares monitored at a sundial; before wristwatches, farmers in some villages also used the stars at night.^4 6 Pumps arrived in the 1950s, and seawater desalination began supplying Muscat and the coast in the early 1970s.¹

The sea now carries the cities: desalination supplied 89% of the public water produced in 2024.² The farms still rely on the aquifers, which are overdrawn. On the coast, FAO described rising salinity as probably the single most economically devastating water problem facing Oman.¹ In Dhofar’s NajdNajd (Dhofar) The Dhofar-Najd plain in southern Oman, which lies over the Umm er Radhuma-Dammam aquifer system. Its groundwater is used for farming and domestic supply. Source: Inventory of Shared Water Resources in Western Asia, chapter 14, UN-ESCWA and BGR (2013), groundwater use rose from about 19 million m³ a year in 1995 to about 139 million m³ in 2021, against modern recharge of about 12 million m³.^7 8 By July 2026, Oman had built 212 dams, 53 of them for groundwater recharge.⁹

One interactive map of Oman's water, built from real geodata. Climate & drought maps the aridity gradient (WorldClim) with warming projections. The Water risk layer's WRI Aqueduct indicators, 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. Shared waters outlines the aquifers that Oman shares with other countries, each drawn in full across the border; hover an outline for the countries that share it. 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.¹⁴ Musandam is an exclave, separated from the rest of the country by the UAE.¹ The Hajar mountains form a 700 km arc from Musandam and rise above 3,000 m at Jabal Shams.^15 14 The Batinah plain covers about 4% of the land but holds over half of the farmland.¹ Desert, sand and gravel plains cover 82% of the country, including part of the Rub’ al Khali.¹

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.¹ Dhofar in the south gets the June–September khareef, and Salalah typically receives about 131 mm a year.^1 16 Rainfall ranges from less than 20 mm in the interior desert to over 300 mm in the mountains.¹ National estimates range from about 60 to 100 mm a year.^1 14 Most wadis flow for only hours or days after a storm.¹

In the World Bank Climate Change Knowledge Portal’s ERA5 reanalysis, averaged over the whole of Oman, about 48 mm of rain falls in a year (1991–2020). Station records and national averages use other sources and baselines, so their figures can differ (the text cites national estimates of about 60 to 100 mm a year). About 40% of the rain falls in March, May and June, and 10 months average less than 5 mm. At such low totals, percentage changes in rainfall between decades mean little in absolute terms.

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.¹⁵ In June 2018 Quriyat recorded a 24-hour minimum of 42.6 °C.¹⁴ Station records show warming of about 0.3 °C a decade since 1980, 1.4 °C in total, with rainfall falling at most stations.¹⁵ Cyclones bring the extremes. Of 176 Arabian Sea cyclones in 76 years, 30 hit Oman directly.¹⁷ Gonu in 2007 caused 50 deaths with 900 mm of rain over two days, and Shaheen dropped 369 mm on Khabourah in October 2021.¹⁸ Cyclone losses between 2002 and 2021 came to about US$7.3 billion.¹⁴

The same reanalysis gives a mean temperature of 27.9 °C for 1991–2020 and a warming of about 0.24 °C a decade over 1971–2022. Station records and national reports use other sources and periods, so their warming rates can differ (the text cites about 0.3 °C a decade since 1980 in station records, from the national report).

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.¹⁴ Heatwave days are projected to rise by 20–40% by 2050 under high emissions.¹⁴ By 2100 daily maximum temperatures in Al Dhahira could peak at 52 °C.¹⁵ Coastal sea temperatures are projected to rise by an average of 1.76 °C by the 2040s, which hurts desalination efficiency.¹⁵ Model ensembles disagree on rain: the World Bank’s multi-model median is wetter by late century.¹⁹

Projected change for Oman

The table gives the CMIP6 multi-model median from the same World Bank portal, as change against 1995–2014. Projections cited in the text may use other models, scenarios or baselines, so their figures can differ.

Oman’s renewable water is about 1,300 million m³ a year, and the national deficit is 316 million m³.^15 20 In 2017, 79% of the rain that fell evaporated.¹⁵ Fresh groundwater lies mainly in the far north and far south, where rain and recharge occur. Elsewhere it is mostly brackish to saline.¹ The largest aquifer stores are Masarrat in Al Dhahirah, at 19,500 million m³, and the Sharqiyah Sands, at 12,000 million m³.¹⁵ Cyclones matter for recharge: Mekunu in 2018 delivered about 3.2 km³ of net recharge to the Najd basin in Dhofar.²¹ Desalination plants now carry the cities; the official 2024 figures are under Supply by source below.²

FAO’s 2008 country profile estimated groundwater depletion at about 134 million m³ a year, and coastal over-pumping had drawn in seawater.¹ FAO AQUASTAT puts total renewable water at about 277 m³ per person a year (2023).¹¹

Supply by source

Public water supply in Oman comes mostly from the sea: in 2024, 462.7 million m³ of the 519.7 million m³ produced (89%) was desalinated, the rest pumped from wells.² Agriculture, which draws on private wells and the aflaj, is outside these figures, and no national balance covering it was found, so no supply mix is charted.

Oman withdrew 1,321 million m³ of water in 2003. Agriculture took 88.4%, municipal use 10.1% and industry 1.5%.¹ The government reserves the fossil aquifers of Dhofar, Al Dahra and Sharqia for urban supply and future needs.¹

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.¹ AQUASTAT’s latest count, for 2020, is 107,100 ha (an official value).²² 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.¹ Wells supply 67% of groundwater withdrawal and aflaj 33%.¹ The 1997 national inventory counted 3,017 working aflaj irrigating 21,606 ha.¹ UNESCO lists falling water tables as a threat to them.⁴ Groundwater recharge dams are covered under Infrastructure.

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.²³

The shift to the sea

Desalination meets 86% of drinking-water supplies but 31% of total water demand, CSIS reported in March 2026.²⁴ 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 2032.²⁵

Use by sector

FAO AQUASTAT’s latest split of water use by sector for Oman, for 2018, puts municipal withdrawals at 130 million m³ a year, while the National Centre for Statistics and Information records 512 to 520 million m³ of public water produced each year from 2022 to 2024.^11 2 No official split replaces it, so none is charted here.

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 its latest estimate (2020). Agriculture’s share of the total moved from 93% in 1994 to 81% in the latest estimate (2019).²²

Agriculture took about 81% of Oman’s water withdrawals in 2020: 1.547 of 1.915 billion m³, with fresh groundwater at 1.532 billion m³ and desalinated water at 0.423 billion for all uses.²² Aflaj irrigated 30% of the irrigated area in 2013 and used 31% of agricultural water, according to the national agriculture strategy, which also says that pumping from wells is “virtually out of control” and that government policy allocates low-cost groundwater to agriculture.²⁷ The aflaj themselves are described under Water use.

Methods and subsidies

Surface irrigation covered about half of the equipped area in 2015 and again in 2020.²² The strategy of 2016 says that in most cases 75% of the equipment value is subsidised, while finding “no indications that it has reduced water use”.²⁷ The ministry reported in 2023 that it supports farmers converting flood irrigation on well lands to drip or sprinklers.²⁸ Oman’s climate reporting lists replacing water-intensive crops such as Rhodes grass with wheat among its adaptation measures.¹⁵ It also says that in the northern agricultural region about 40% of farmland is irrigated with water above 5 dS/m, which it attributes to reduced recharge, unauthorised well drilling and over-extraction.¹⁵

Treated wastewater

The 2016 strategy found that virtually none of the non-conventional water was used in agriculture.²⁷ In 2018, according to a press report on the voluntary national review, 68 plants produced about 94 million m³ of tertiary-treated water, 61% of it used in agriculture, afforestation, cooling and coastal aquifer injection, without a separate figure for agriculture.²⁹ In October 2026 the press reported the result of an eight-year ministry trial in which lemon trees irrigated with regenerated water kept growth and production comparable to trees on desalinated groundwater; the ministry plans to supply regenerated water to farmers in Al Shakhakhit, Barka.³⁰ Other agricultural water projects are on the Agriculture & Food hub.

Oman had built 31 major recharge dams since 1985 by the late 2000s, plus many smaller structures.¹ Its dam count has since climbed fast, from 155 in 2018 to 212 by July 2026,^15 9 with 458.79 million m³ of storage. They include 53 groundwater recharge dams holding 108.6 million m³, and 33 more dams are planned.⁹ Wadi Dayqah near Quriyat, one of the largest dams in the Arabian Peninsula, holds 100 million m³ behind a 75 m wall.³¹ Muscat opened two flood protection dams in February 2025, Wadi al Jifnain and Al Jufainah.^32 33 Four more dams worth RO243 million, agreed in collaboration with the Ministry of Finance and the Islamic Development Bank, include Wadi Majlash at 140 million m³.²⁰ A treatment plant at Wadi Dayqah, agreed in 2025, will have a production capacity of 35,000 m³ a day for drinking water and 30,000 m³ for irrigation.³⁴

Tracked projects

Open the project database for Oman

Desalination and transmission

Desalination output rose from 34 million m³ in 1995 to about 109 million m³ in 2006.¹ Nama Power and Water Procurement is the single buyer of water capacity.³ 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 191,000.³ Ghubrah III, at 300,000 m³/day, is expected in February 2027. Salalah III has supplied Dhofar with 113,650 m³/day since 2021.³ On the utility’s own figures, about 90% of the 445 million m³ produced in 2025 was desalinated, an official of Nama Water Services said in May 2026.³⁵ Pipelines carry that water inland. The 230 km Sohar–Dhahirah line opened in January 2023.³⁶ By November 2025 Nama Water had completed more than 620 km of new mains and 27 reservoirs.³⁷

Wastewater, networks and reform

In 2024, 67 wastewater treatment plants treated 119.5 million m³ of wastewater.² Between 2021 and 2025 the number of treatment plants grew by 9%, and the wastewater treatment rate reached 98%.³⁸ In late June 2026 a consortium led by SUEZ won a 15-year, €2 billion performance contract, reported locally as RO878 million, for Muscat and North and South Sharqiyah.^39 40 Its area has 22 wastewater treatment plants, 10,700 km of water pipelines and more than 400,000 smart meters. The contract aims to cut water losses there from 34% to 11% by 2040.⁴⁰ By May 2026 an aquifer storage field pilot was under way in the Sharqiyah Sands aquifer basin to store surplus desalinated water.³⁵ In March 2026, 97 water and wastewater projects worth RO966 million were under way.³⁸

The 2026 war

The war reached Oman’s coast. On 11 March 2026 News18 reported, citing Oman TV, that drones it described as Iranian struck oil storage at the Port of Salalah, one of the country’s main ports; the security firm Ambrey confirmed the attack.⁴¹

Dams and reservoirs

FAO called rising salinity probably the single most economically devastating water problem facing Oman.¹ Near the sea, 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.¹ Between 1984 and 2005 the Seeb–Suwaiq coast lost 2,714 ha of irrigated land to saltier water, and a saline front was reported 12 km inland at Barka.⁴³ A study of about 58,000 Batinah wells from 1990 to 2018 found salinity rising with urban growth and over-pumping.⁴⁴ At current pumping, a model projects very saline water moving 0.8 km further inland at Wadi Al-Jizi by 2040.⁴⁵

Soils are salting up as well. On eight Batinah farms, soil salinity rose from low to highly saline between 1993 and 2020.⁴⁶ Agrochemicals are a hazard because the groundwater is unconfined and the soils sandy.¹ At sea, a 2008–09 red tide shut several desalination plants in Oman and the UAE for up to two months.²⁴ A tanker damaged off Yemen in June 2026 later ran aground and leaked oil off Oman.⁴⁷ In 2026 an oil spill from a damaged tanker threatened about 40 km of coast near Ras Madraka and Masirah Island.⁴⁸

The reported indicators

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.⁸

The southern Umm er Radhuma–Dammam

This system covers 678,000 km², of which 249,000 km² lie in Oman.⁸ It is used only in Oman’s Dhofar–Najd region and around Jebel Hafit in the UAE. ESCWA’s 2013 inventory listed average annual abstraction of 45 million m³ for Oman and 7.7 million m³ for the UAE, while its text estimated about 38 million m³ a year for Oman.⁸ Modern recharge in the Najd averages only about 12 million m³ a year.⁸ Yet Najd groundwater use rose from about 19 million m³ a year in 1995 to about 139 million m³ in 2021.⁷ ESCWA identified Jebel Hafit and the Oman–Saudi–Yemen border area as areas that could be of interest for joint management.⁸

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.⁸ Oman taps it in Al Dhahirah, mainly through aflaj.⁸ Water levels have fallen by up to 50 m west of Al Ain, and efforts to launch joint management have produced no concrete results.⁸ IGRAC’s mapping, in the record below, does not list it as a transboundary aquifer.

The record

Shared aquifers

• Umm er Radhuma-Dammam Aquifer System (South): Rub' al KhaliSaudi Arabia, UAE, Yemen · data moderate

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.⁴⁹ Another renamed the electricity regulator as the Authority for Public Services Regulation.⁵⁰ 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.⁵¹ By 2022 the merged company was part of the Nama group.⁵²

Law and tariffs

A 1988 royal decree declared water a national resource, and a 2000 decree regulated wells and aflaj.¹ The Water Resources Protection Law of 2000 requires a ministry licence for any change to a falaj channel, and well licences carry fees.⁵³ Rules recorded by FAO bar new wells within 3.5 km of a falaj mother well.¹ A sector law of June 2023 lets the regulator set network standards and, with cabinet approval, liberalise the market.⁵⁴ Tariffs have risen annually since 2021 towards a cost-based tariff.⁵⁵ In Dhofar in 2025 the residential tariff was 3 baisa a gallon for up to two accounts and 3.5 baisa for further accounts, and the non-residential tariff 6 baisa.⁵⁶ In March 2024 the regulator announced a 70% reduction in water-service connection fees.⁵⁷ The National Water Sector Master Plan runs from 2015 to 2040.¹⁵

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.^{15 24 41 47} New dams, the Wadi Dayqah treatment plant and aquifer banking in the Sharqiyah Sands are the hedges.^20 34 35

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.^20 45 14 The aflaj carry a lesson the region keeps relearning: institutions outlast pumps.