Speaking to the state-run Al-Ahram newspaper, the institute's director said Egypt will require an extra 21 billion cubic metres (bcm) of water per year from Africa's longest river to meet the needs of industry, agriculture and households in 40 years' time.
Egypt is currently entitled to 55 bcm of the Nile's total annual flow of around 84 bmc under a treaty with the eight other countries which share the river basin.
Fadya Abdel-Salam, director of the NPI, said that if Egypt's current share of the Nile remains the same, by 2050 each Egyptian will have a Nile "stake" of 400 cubic metres in the river's waters -- well below the global water poverty index of 1,000 cubic metres.
Should the Nile's total flow remain constant, Egypt will eventually need some 92 per cent of the 6,695 kilometre-long river's waters, according to NPI's estimate.
Official statistics last week showed that Egypt's population is 82 million, with eight million other citizens living abroad.
NPI's research estimates that Egypt's industrial and agricultural needs will rise by 2050 to 10.5 bcm and 10.4 bcm, respectively.
According to the UN's Food and Agriculture Organization, Egypt's water resources are limited to the Nile River, deep ground water in the Delta, the Western Deserts and Sinai, sporadic rainfall and flash floods.
Agriculture accounts for 85 per cent of water demand, while domestic and industrial use makes up 8 and 6 per cent respectively. The remaining one per cent is used in navigation and hydropower.
In March 2011, Ethiopia said it planned to build a dam on the Nile despite a long-running row with Egypt over use of the river.
Egypt is a member in the Nile Basin Initiative (NBI), a partnership among Nile states aimed at sharing the river's socio-economic benefits and promoting regional security.
Nine countries are involved in the initiative: Egypt, Sudan, Ethiopia, Uganda, Kenya, Tanzania, Burundi, Rwanda and the Democratic Republic of Congo