In examining international law, it is necessary to distinguish between Israel's obligations as an occupying state to the population under its control on one hand, and the use of water sources shared by Israel and the Palestinians, which are considered international waters, on the other.

A. Administration of the water sector in occupied territory

1. Prohibition on altering legislation

Article 43 of the 1907 Hague Regulations prohibits an occupying state from changing the legislation in effect prior to occupation. The military orders that Israel issued regarding the water resources and the supply of water in the Occupied Territories significantly changed the legal and institutional structure of the water sector. The water resources in the Occupied Territories were integrated into the legal and bureaucratic system of Israel, severely limiting the ability of Palestinians to develop those resources.

2. Illegal utilization of water resources

Article 55 of the Hague Regulations limits the right of occupying states to utilize the water sources of occupied territory. The use is limited to military needs and may not exceed past use. Use of groundwater of the Occupied Territories in the settlements does not meet these criteria and therefore breaches article 55.

3. Discrimination between Palestinians and Israeli Settlers

Article 27 of the Fourth Geneva Convention of 1949 prohibits an occupying state from discriminating between residents of occupied territory. The quantity of water supplied to the settlements is vastly larger than that which is supplied to the Palestinians. Similarly, the regularity of supply is much greater in the settlements. This discrimination is especially blatant during the summer months when the supply to Palestinians in some areas of the West Bank is reduced in order to meet the increased demand for water in the settlements receiving their water from the same pipelines.

B. Utilization of shared international water sources

Under international law, the main principle for division of shared water between states is the principle of equitable and reasonable use. This principle is based on the limited-sovereignty doctrine, which provides that, because all parts of the drainage basins of watercourses are hydrologically interdependent, states are not allowed to utilize water located in their territory as they wish, but must take into account the other states that share the resource.

This principle does not state a precise formula quantifying the rights of each state sharing an international watercourse. Rather, it lists the factors to be considered in negotiations between the states to determine the division. Article 6 of the UN Convention on the Law of the Non-Navigational Uses of International Watercourses enumerates seven of these factors:

1. The natural features of the shared watercourse (geographic, climatic, hydrologic, and the like);
2. The social and economic needs of the watercourse states;
3. The population dependent on the watercourse in each watercourse state;
4. The effects of the use of the watercourses in one watercourse state on other watercourse states;
5. Existing and potential uses of the watercourse;
6. Conservation, protection, and development of the water resources of the watercourse and the costs of measures taken to that effect;
7. The availability of alternatives to a particular planned or existing use.

Taking into account the components of the principle of equitable and reasonable use, examination of the current division of water between Israel and the Palestinians leads to the conclusion that this division violates Palestinian rights and contravenes international water law.