Water in Yemen

Yemen has no perennial rivers and depends entirely on rainfall, groundwater and flash floods.¹ Within about thirty years, farming shifted to tubewellTubewell A well made by sinking a long, narrow steel tube or plastic (PVC) pipe into the ground to draw up groundwater. Source: Tube wells, AGROVOC Multilingual Thesaurus, FAO irrigation, much of it devoted to growing qatQat (khat) An evergreen shrub or small tree whose leaves and young buds are chewed for their mild stimulant effect. Native to the Horn of Africa and the Arabian Peninsula, it is an important cash crop in Yemen. Source: Khat, Encyclopædia Britannica, and the aquifers are now pumped far faster than they recharge.¹ Since 2015, war has damaged networks, wells and treatment plants, and divided the institutions that manage water.^2 3 4 Millions of people now depend on humanitarian water and sanitation assistance.⁵

For most of Yemen’s history, farming depended on rain and floods. In the first millennium BCE, the SabaeansSabaeans A people of South Arabia in pre-Islamic times who founded the kingdom of Sabaʾ, the biblical Sheba. They built most of what is visible today of the dam at Marib. Source: Sabaean, Encyclopædia Britannica built the Marib dam, which fed irrigation canals in what UNESCO calls the largest artificial oasis in ancient Arabia.⁶ The dam worked mainly by diverting seasonal flash floods, which watered about 9,600 hectares at its peak.⁷ After breaks in the 5th and 6th centuries CE, it was possibly destroyed for good in the 6th century.⁸ In the highlands, terraces were built to retain water and keep the land fertile.⁹ In 1984, Sheikh Zayed of the UAE laid the cornerstone of a new Marib dam he had offered to fund, and the dam opened two years later.¹⁰ By then, Yemen had begun mining its groundwater: from the mid-1980s, use exceeded recharge.¹

The overdraft shows in the highlands, where water tables commonly fall 2 to 6 m a year.¹¹ The war has added physical damage to this depletion. A World Bank assessment of 16 cities in 2020 found that 38% of water and sanitation assets were damaged or destroyed.² In 2020, tankers were reported to supply around 40% of the urban population, while solar power increasingly pumped private wells.³ Suspected cholera cases passed two million by December 2020,¹² and researchers link the epidemic to the destruction of water and sanitation infrastructure since 2015.³ Water is now managed across a political divide: the internationally recognised government sits in Aden, while the Houthi authorities in Sanaa control areas holding about 70% of the population.⁴

One interactive map of Yemen'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 Yemen 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.

Yemen covers 527,970 km² on the south-western corner of the Arabian Peninsula, with about 2,200 km of coast on the Red Sea, the Gulf of Aden and the Arabian Sea.^11 17 It has no perennial rivers and depends entirely on rainfall, groundwater and flash floods.¹

Four landscapes

The Tihama and the southern coastal plains are flat and hot, with temperatures of 27–42 °C and less than 200 mm of rain a year.¹¹ Behind them the mountain massif rises to 3,760 m. Its steep western and southern slopes catch 300–500 mm a year on average, and more than 1,000 mm in places.¹¹ The eastern plateau around Hadramawt falls from 1,800 m to the desert edge and gets under 100 mm, though its floods can be devastating.¹¹ The Ramlat as-Sab’atayn sand desert lies between the two, and the Rub’ al Khali runs north into Saudi Arabia.¹¹

Two rainy seasons

Rain comes in two seasons. The Red Sea Convergence Zone brings it to the western highlands from March to May, and the monsoon belt reaches Yemen from July to September.¹¹ The World Bank puts the national average at about 190 mm a year.⁴ The western highlands receive 200–600 mm, while the coastal plains and eastern deserts often get under 50 mm.⁴ The national mean temperature is 25.5 °C.⁴ It ranges from 10–22 °C in the highlands to the western coastal plain, where temperatures above 50 °C are common.¹⁷

In the World Bank Climate Change Knowledge Portal’s ERA5 reanalysis, averaged over the whole of Yemen, about 147 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 a national average of about 190 mm a year from the World Bank). About 45% of the rain falls in July, August and September, and 3 months average less than 5 mm. Average rainfall in 1993–2022 was about 22% lower than in 1951–1980, and single years swing widely around that.

A warmer, more extreme climate

Yemen warmed by 0.42 °C a decade between 1971 and 2020, fastest in Al Jawf.⁴ Rainfall fell slightly, by 6.25 mm a decade, a trend the World Bank does not treat as significant.⁴ Extremes are the sharper story. Cyclones Chapala and Megh struck in November 2015, and on Socotra they damaged water pipelines and wells.¹⁸ Floods between April and November 2024 affected more than 688,000 people, killed 240 and destroyed numerous water sources.¹⁹ The same year brought severe drought as well.⁴ In a 1-in-100-year event, more than five million Yemenis would be exposed to a wet-bulb temperature above 35 °C, mostly in Hodeidah, Aden and Hadramawt, the World Bank estimates.⁴

The same reanalysis gives a mean temperature of 25.8 °C for 1991–2020 and a warming of about 0.39 °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 0.42 °C a decade over 1971–2020 from the World Bank).

Projections

The World Bank projects national temperatures up to 1.69 °C higher by 2050 under a pessimistic scenario.⁴ Rainfall is projected to rise in every scenario, by 15% even in the pessimistic case and by up to 43%.⁴ It is expected to fall in more intense bursts between longer, hotter dry spells.⁴ Under one scenario in Yemen’s second national communication, the sea at Aden rises by 0.25 m by 2050 and 0.54 m by 2100.¹⁷

Projected change for Yemen

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.

Yemen receives 67–93 km³ of rain a year, concentrated on the western and south-western highlands.¹¹ In 2005 renewable resources of about 2,100 million m³ a year were topped up by about 1,300 million m³ mined from deep aquifers.¹ The World Bank’s 2024 water balance puts total runoff at 2.5 billion m³, of which 1.0 billion m³ is available for spate diversion. It puts average groundwater recharge at around 316 million m³.⁴ Other estimates differ widely: FAO put renewable groundwater at about 1.5 km³ a year.¹¹

The aquifers are layered. In the Sanaa basin, a shallow alluvial aquifer lies above the deep Tawilah sandstone, which policy aimed to keep for the city’s drinking water.²⁰ In the Tihama, Wadi Surdud crosses a mountain aquifer, a shallow wadi aquifer and a coastal aquifer.¹⁷ Surface runoff of about 270 million m³ a year still reaches the sea.¹¹ Desalination and reclaimed wastewater remain negligible.¹

Supply by source

FAO AQUASTAT’s figures for Yemen’s water withdrawal by source come from different years (groundwater and surface water 2015, desalination 2006), and no national balance was found, so no supply mix is charted.¹⁴

Yemen began mining its groundwater in the mid-1980s, when use first exceeded recharge.¹ Total withdrawal rose from 2.9 km³ in 1990 to 3.4 km³ in 2000. That year agriculture took 90%, municipal use 8% and industry 2%.¹¹ Irrigation alone consumed 130% of renewable resources by 1990 and more than 150% by 2005.¹ Total water demand is projected to reach 3.9 billion m³ by 2050.⁴

The tubewell boom

Private drilling did the damage. FAO counted 52,000–55,000 active wells and about 800 drilling rigs, mostly unpermitted. In May 2005 only 70 rigs and 1,000 wells were licensed.¹¹ Over-pumping on the coasts draws in seawater.¹¹ Regulation came late (see Governance). Diesel price rises were tried as a brake, but the World Bank found no measured effect on groundwater overdraft.¹

Qat

Qat covered 122,844 ha in 2004, 10% of the cultivated area, and 99,504 ha of it was irrigated.¹¹ Its area more than tripled in 25 years.¹¹ The World Bank did not consider qat a heavy water user. But its area was growing 9% a year, so it took a rising share of the water, and in some areas half of irrigation abstraction went to it.¹ By the 2009 census qat covered 11.3% of cultivated land, and it was separately estimated to contribute 41% of the value of agricultural products.²¹ The World Bank’s 2024 climate report says qat is responsible for over 30% of groundwater withdrawal.⁴ A national debate on qat, launched in 1999, had no discernible effect on behaviour.¹

The Sanaa basin

Irrigated land in the Sanaa basin grew from under 3,000 ha in 1985 to about 23,400 ha in 2000. About 13,000 wells were drilled without regulation, helped by a 90% subsidy on pump diesel.²² By 2005 abstraction of about 250 million m³ a year was more than four times the nominal recharge of 42 million m³.¹ The World Bank warned that the deep fossil water could be exhausted within twenty years if nothing changed.¹ Between 2005 and 2009, 614 wells were dug illegally in the basin, against 106 licensed.²⁰

Irrigated land and spate floods

All 454,310 ha of fully or partly controlled irrigation drew on groundwater in 2004, most of it from tubewells.¹¹ Spate irrigation swings with the floods. Its command area of 217,541 ha was fully irrigated in 2001, but only 89,363 ha were watered in 2004.¹¹ Irrigation efficiency runs at only 35–45%.¹¹

Cities and war

Aden’s Bir Nasr well field fell more than 8 m between 1998 and 2003. By mid-2004 the city’s 24-hour supply had been cut to 12 hours.¹ In 2020, private supply through tankers was reported to cover around 40% of the urban population, although the actual share was probably higher.³ Solar panel sales rose more than 2,000% between 2015 and 2016. Solar power increasingly pumps the private wells of powerful elites, for farming and for sale to tankers.³ Rising fuel and freight costs were pushing up the cost of trucked water in mid-2026.²³

Use by sector

Withdrawals over time

FAO’s AQUASTAT estimates put Yemen’s freshwater withdrawals at 2,922 million m³ in 1990 and 3,565 million m³ in its latest estimate (2005). Agriculture’s share of the total stayed at about 91% between 1994 and the latest estimate (2005).

Irrigation took 83% of water demand in 2020 in the World Bank’s model, and more than 40% of irrigation demand was unmet; the estimated groundwater deficit was 2.6 billion m³.⁴ Before the conflict qat was estimated to use 36% of renewable water and 32% of groundwater withdrawals, and the Bank thinks the shares have probably risen.²⁵ Water rights remain in practice with the owners of an estimated 100,000 or more deep wells.²⁵ In the southern and eastern governorates, floodwater irrigates 70% of agricultural land, according to UNDP.²⁶ The spate schemes and well numbers are under Water use.

Land and methods

UNDP says qat occupies 16% of farmed land but consumes over a third of irrigation water.²⁶ FAO’s estimate for 2004, 680,000 ha equipped for irrigation, has not been updated.²⁷ The war has hit the spate systems: Wadi Siham was running at 50% of capacity in 2017,²⁸ and the Conflict and Environment Observatory found 46% of the cropland in wadis Zabid and Rima, 751 km², in distress by a biomass index comparing 2009–2013 with 2014–2019.²⁹

Wells and rules

The Bank’s 2024 policy note recommends limits on withdrawals, control of solar pumping, remote sensing to enforce a cap and a National Irrigation Authority.²⁵ It also notes that fuel subsidies and weak enforcement of qat taxes distorted incentives before the war and that solar pumps now drive unregulated withdrawals.²⁵ Groundwater levels in April 2021 were the lowest since satellite records began in 2002, which the Conflict and Environment Observatory suspects reflects solar pumping.³⁰ Qat area grew by more than 40% in some regions between 2016 and 2021, according to the World Bank climate report.⁴ UNDP promotes coffee as a replacement for qat; no state limit on qat was found.²⁶

Treated wastewater

With Japanese support FAO has installed small treatment plants that produce irrigation-quality water in the Sana’a basin,³¹ and the World Bank lists wastewater reuse in irrigation among recommended investments.²⁵ No current area or volume was found. The register lists the Marib Dam; more irrigation dams are on the Agriculture & Food hub.

Yemen’s water infrastructure is small-scale and badly damaged. Most of its dams are small: FAO counted 347 storage dams, and the rebuilt Marib Dam, financed by the UAE, holds 400 million m³.¹¹ Displacement to Marib has increased the population at risk downstream of that dam.⁴ In 2005 the World Bank reported poor design, contracting and construction standards in the watershed-dam programme, while Yemen’s national water strategy (NWSSIP) included an overhaul of the dams programme.¹

Tracked projects

Open the project database for Yemen

Spate and groundwater schemes

Donor projects rebuilt traditional flood irrigation. The Irrigation Improvement Project improved irrigation and flood control on 26,000 ha in Wadi Tuban and Wadi Zabid.³² A groundwater and soil conservation project delivered 62 small and medium spate schemes and equipped 50,868 ha with modern irrigation by 2012.³³ Around Sanaa, 11 recharge dams were rehabilitated by 2010.²⁰

Networks and the war

Treatment plants were overloaded long before the war. Sanaa’s plant, originally designed for 25,000 m³ a day, received more than 50,000 m³.¹¹ In 2007, 56% of urban residents had access to network water supply and 31% to sewerage.³⁴ By 2021 public networks covered only a third of city dwellers, down from half before the war.³⁵ A World Bank assessment of 16 cities in 2020 found 38% of water and sanitation assets damaged or destroyed.² Both desalination plants assessed had been destroyed. Of 493 wells, 172 were damaged or destroyed, as were 45% of the primary and transmission mains.² Damage to the sector was put at US$421–515 million.² Between April 2015 and December 2017, the Yemen Data Project documented 74 airstrikes on water infrastructure, including desalination and bottling plants.³⁶

The war has put water infrastructure in the line of fire beyond Yemen too. The Houthis attacked desalination plants in Saudi Arabia in 2022.³⁷ On 20 July 2026 the Sanaa-based authorities declared a maritime blockade of Saudi ports, and Saudi Arabia struck Houthi-held Al-Hudaydah.²³

World Bank-funded rebuilding runs through the UN. The first World Bank urban services emergency project reached more than 1.2 million people and put solar power on municipal and rural wells.³⁸ Its successor, approved in June 2021, had restored water to 924,103 people by April 2026, 92% of its target.³⁹ In August 2026 Aden began preparing a Saudi-financed seawater desalination plant with a first phase of about 10,000 m³ a day.⁴⁰

Dams and reservoirs

Over-pumping has turned coastal groundwater salty. At Al-Jar in the Tihama, 8 km from the Red Sea, conductivity rose from 225 to 3,480 µS/cm as seawater intrusion reached an area where about 2,000 wells had been drilled for mango orchards.¹¹ The major coastal aquifers along the Red Sea and in the western Gulf of Aden face rapid depletion and seawater intrusion.¹ In the Sanaa basin, evidence of groundwater-quality deterioration is mainly in the urban area, where wastewater seeps into the ground from unsewered districts, and immediately downstream, where urban sewage effluent is discharged and reused.²²

Of 74 million m³ of wastewater produced in 2000, only 6 million m³ a year of treated wastewater was used in farming. Uncontrolled reuse watered vegetables and fruit around Sanaa.¹¹

Cholera

Before the war, Yemen reported cholera in 10 of the 40 years from 1971 to 2010. An outbreak in 2011 caused 31,789 cases and 45 deaths.⁴¹ The war then damaged water systems, including by airstrikes (see Infrastructure). From 28 September 2016 to 12 March 2018, 1,103,683 suspected cholera cases and 2,385 deaths were reported.⁴¹ By December 2020 suspected cases had passed two million, with more than 3,500 deaths.¹² Cholera surged again in 2024, with 260,552 cases and 879 deaths reported.¹² In 2026 cases fell sharply, to 6,625 suspected by 9 August.⁴²

The reported indicators

On the latest values each country reports for SDG indicator 6.3.1, Yemen’s 28% (2022) ranks 15th of the 17 countries covered here that report it; years differ by country. The regional comparison is in the wastewater and reuse dashboard.

Yemen has no perennial transboundary river.¹ Some groundwater and surface drainage may cross into Saudi Arabia, but FAO found no data on it.¹¹ Its shared waters include the Wasia–Biyadh–Aruma aquifer system with Saudi Arabia and the Umm er Radhuma–Dammam system with Saudi Arabia, Oman and the UAE; neither system is covered by a water agreement.^43 44

The aquifers

The Wasia–Biyadh–Aruma system, shared with Saudi Arabia, covers about 157,000 km² and holds fresh water. Its maximum extraction potential is estimated at about 500 billion m³.⁴³ Use is limited to nomads and the Sharurah–Al Abr border posts. ESCWA sees the aquifer as a possible future source for Najran and Sa’dah.⁴³ Natural uranium in the sandstone may pose a radionuclide risk, and no cooperation between the two states has been reported.⁴³

The southern Umm er Radhuma–Dammam system is shared by Oman, Saudi Arabia, the UAE and Yemen. It covers 678,000 km², of which 72,000 km² lie under Yemen’s Hadhramaut–Al Mahra plateau.⁴⁴ ESCWA flags the border area where Oman, Saudi Arabia and Yemen meet as a candidate for joint management.⁴⁴

The record

Shared aquifers

• Umm er Radhuma-Dammam Aquifer System (South): Rub' al KhaliOman, Saudi Arabia, UAE · data moderate
• Wajid Aquifer SystemSaudi Arabia · data good
• Wasia-Biyadh-Aruma Aquifer System (South): Tawila-Mahra/Cretaceous SandsSaudi Arabia · data moderate

Yemen built its water institutions in layers. A national urban utility was set up in the 1980s and a rural water authority in the early 1990s.¹ The National Water Resources Authority followed in 1996.³⁴ The Ministry of Water and Environment was created in 2003.¹¹ A 1997 reform plan began handing urban water to local corporations.³⁴ The Water Law, enacted in August 2002 and amended in 2006, remains the legal base; in November 2002 the cabinet declared Sadah, Sanaa and Taiz protected areas.¹¹

Reform slowed before the war. By 2009 tariff increases were mired in local and national politics, and little progress had been made on private participation.³⁴ Tariffs are set locally. In 2005 the World Bank judged Sanaa’s structure neither pro-poor nor water-conserving.¹ The update of the national water strategy aimed for full urban cost recovery by 2015.³⁴

The war split the state. The internationally recognised government sits in Aden, while the Houthi authorities in Sanaa control areas holding about 70% of the population.⁴ The agrometeorological network now runs through separate agriculture ministries on each side.⁴ Monitoring has collapsed: of the 354 stations the water resources authority ran in 2010, 70% are out of service, destroyed or stolen.⁴ By 2021 line ministries and local authorities could no longer deliver urban services, so donor projects worked through the UN with the local water corporations.³⁵ Civil society fills part of the gap: a 2026 mapping examined 53 organisations working in water.⁴⁵

The need remains vast. In June 2026, 14.4 million people required humanitarian water and sanitation assistance, and only 14% of the US$178.7 million appeal was funded.⁵ Water scarcity affects 301 of Yemen’s 333 districts.⁵

Water sits near the centre of any Yemeni recovery. The immediate task is repair: networks, wells and treatment plants damaged in the war, and a monitoring network that has largely gone dark.^2 4 The longer task is groundwater. Since the World Bank’s 2005 warning on Sanaa’s deep fossil water (see Water use), solar irrigation pumps have spread widely, particularly among wealthier qat farmers, adding to the pressure on Yemen’s groundwater.⁴⁶

Climate adds a twist. Rainfall is projected to rise, but in more intense bursts, so spate systems, terraces and flood protection matter alongside new supply.⁴ Long-term security of municipal supply may require desalination, but only with a better enabling environment.⁴ The institutions that would deliver it are split across political divides.⁴