Tapping strategic and local Sinai groundwater reservoirs for development purposes historically stood divided between traditional Bedouin and military use until the late 1970s. Sinai is the peace front of the Middle East, where water plays a major role in stabilising its inland and coastal communities. A “water carrier” drawn across the Suez Canal on an Egyptian postage stamp in 1966, with the English-language title “Development of Sinai”, represents how water has always played a vital role. It reflects the more than a half-century-old plan for how Sinai agriculture lands could be irrigated for mass production. This water carrier later became the partially implemented Al-Salam Canal along the Mediterranean coastal plain and Suez Canal in North Sinai (1997-2006). The canal was designed to deliver irrigation to 400,000 feddans (currently, a maximum of 50,000 to 190,000 feddans are irrigated by the canal). The longstanding plan to deliver Nile water to Sinai did not undermine the exploration of the peninsula's groundwater resources. Among the first full-scale regional capacity studies for Sinai water were the “Water Supply and Cost Study” by USAID in 1985, and “Sinai Water Resources Study” by the European Economic Community in 1980s. These were followed by the “North and South Sinai Groundwater Resources Study” by the Japan International Cooperation Agency (JICA) in 1992 and 1998. These strategic studies capped a series of regional and local studies of the peninsula, dating back to the 1940s. SINAI IN THE 21ST CENTURY: Where does Sinai water stand today, between resources (Nile water carriers and pipelines, groundwater reservoirs, surface water/flash floods and desalination efforts) and future use (irrigation, industrial and household)? Sinai water resources and their use strategy are being determined in the 21st century amid rapidly increasing population in Egypt, geopolitical challenges in the Nile Basin, and global warming. The answers vary according to local geography and the type of available water resources. The abovementioned studies focussed on the Mediterranean coastal plain and the eastern water springs zone in North and Central Sinai, and Al-Raha, Al-Markha and Al-Qaa plains along the Gulf of Suez in South Sinai, compared to other inland areas. The surface water/flash floods and desalination options were less considered compared to water carriers, pipelines and groundwater for 50 plus years. It might be argued that the use of the groundwater option prevailed as a fast-starting alternative for Sinai irrigation since the “Development of Sinai” postage stamp in 1966. This occurred due to the high infrastructure and time-consuming cost of water carriers and pipelines, in addition to the urgent national need to create new agriculture communities outside the Nile Valley, and other challenges. One example in North Sinai is the groundwater reservoir in Al-Arish-Rafah area (30 kilometres along the coast, 15-20 kilometres wide, and 80-100 metres deep, according to the 1992 JICA study). Total pump volume was estimated to båçe 90,000 cubic meters per day. The reservoir is characterised by low salinity and a 20-plus-year life period at the same extraction and cropping rate, depending on the recharge rate under changing conditions. This example brings us closer to the answer to the question posed, in investigating, planning and continuous monitoring. Some major Sinai water studies and implementation projects did not enjoy those qualities in late 1980s, according to the assessment report of the British Geological Survey in 1988-1989: “Despite 75 per cent spend rate of phase I ... project documentation, the quality of data collected, data storage and data analysis were all found to be poor.” There is no doubt that some Sinai water capacity assessment projects similar to the one of JICA provide a solid scientific answer to our question during a concentrated period of time (the 1990s), though monitoring is a matter of continuous follow up by specialised central and local authorities, which was not achieved for the project mentioned immediately above. LOCAL WATER SUPPLY OPTIONS: Sinai groundwater reservoirs (local and strategic) lie under a network of asphalt roads and dirt tracks across the peninsula, connecting localities and/or groundwater tapping points (water wells). Those manmade watering points are distributed all the way from sea level up to its highest plateau. Bir Abu Rumiel is the highest water well in Sinai and all of Egypt (2,500 metres above sea level), close to the summit of Mount Catherine (2,642 metres above sea level) and only reachable by foot nowadays. One of the most dominant features of late 20th/early 21st century water management is the “white/blue trucks” of the public water company, dotting the dirt tracks whilst on the move. They distribute water between Bedouin localities to cover an increasing household use of settled communities inland. Some major coastal communities are supplied by Nile water using an extended network of pipelines. Between inland reliance on the white/blue trucks and the economic infeasibility of extending centrally fed pipeline networks to all inland localities, the government in Cairo needs to reconsider the construction of local water supply networks, fed by inland desalination plants. This option was explored in earlier studies, and it succeeded in East-Central Sinai by constructing three accessible desalination plants, under the “Livelihood and Income from the Environment in Sinai (LIFE Sinai)” project by USAID in 2008-2012. The utilisation of surface water/flash floods is another understudied option on the local level. This option is meant to supply water for both local agriculture and household use. Despite its understudied status, a series of 20-plus water dams were constructed (aiming to reach 100) under the “Mountain Lakes for Floodwater Harvesting in South Sinai” project by the Arab Organisation for Agricultural Development (AOAD) in 2015. It follows the same example of another 20-plus water dams that were constructed by an NGO in the mountain area around the town of St Catherine. All local water supply options need to consider traditional local Bedouin water knowledge, especially when it comes to projects for floodwater harvesting. A feasible matrix of options is only achievable through deep understanding of the capacity of Sinai water resources and their multipurpose use at a given time. Above all, continuous monitoring of rapid changes. This “Development of Sinai” postage stamp was issued by the Egyptian National Post Organisation under the United Arab Republic in 1966, on the 14th anniversary of the 23 July 1952 Revolution, showing a water carrier transferring Nile water across the Suez Canal and turning North Sinai into an agricultural land, rich with green trees, settled communities and the ancient symbol of the Egyptian wheat harvest. The writer teaches at Durham University and is founder of Sinai Peninsula Research.