Equitable Utilisation of Transboundary Waters

The principle of equitable and reasonable utilisation means that every state sharing a transboundary watercourse is entitled to a fair opportunity to use it, while respecting the comparable rights and interests of other riparian states. Equity does not require an equal division of water; it requires a context-specific balancing of relevant factors to achieve sustainable and beneficial use.

Legal content of the principle

Under Article 5 of the 1997 UN Watercourses Convention, watercourse states must use an international watercourse equitably and reasonably, with a view to optimal and sustainable utilisation, adequate protection, and benefits consistent with the interests of all concerned states.

• Equitable participation combines each state's right to utilise the watercourse with its duty to cooperate in its protection and development.
• No riparian state automatically possesses an exclusive or superior claim merely because it is upstream or downstream.

How equity is determined

Under Article 6, equity is assessed by considering all relevant factors together; no single factor is inherently decisive.

• Relevant natural conditions include geography, hydrology, climate, ecology and the watercourse's physical characteristics.
• Relevant human considerations include social and economic needs, the population dependent on the watercourse, and existing and potential uses.
• The effects of one state's use on another, conservation measures, availability of alternatives and the costs of substitution are also considered.
• Under Article 10, no category of use has inherent priority, although special regard must be given to vital human needs.

Relationship with other duties

Equitable utilisation operates alongside the duty under Article 7 to take all appropriate measures to prevent significant transboundary harm. The Convention therefore emphasises due diligence, cooperation and balancing rather than an absolute guarantee that no harm will ever occur.

• States should exchange available information and cooperate regularly concerning the condition and planned uses of the watercourse.
• If significant harm nevertheless occurs, affected states should consult on eliminating or mitigating it, with due regard to equitable utilisation.

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