Margem Sul's water system may change: Government is exploring bringing water from Castelo de Bode and Tejo

The Portuguese government is preparing a new system to improve the water security of the Margem Sul region, opposite Lisbon. Agência Portuguesa do Ambiente (APA) and Águas de Portugal were given the task of preparing within 120 days the technical solution for transferring surface water to the area from the Castelo de Bode reservoir and/or the Tagus River.

The decision was published in Diário da República on September 9. Therefore, the project is not only at the stage of a political statement; It became an official government directive. citeturn1search1

Why does Margem Sul need a new water source?

Margem Sul's drinking water system relies heavily on the Tejo-Sado groundwater system.

According to the government, such high dependence on a single main water source; It poses a strategic risk for the region in cases such as drought, deterioration in water quality or technical failure. citeturn1search1

Recent water supply problems in Almada were also cited as reasons for the need for an alternative source.

The plan does not mean completely abandoning existing groundwater. The aim is to create an alternative in case of any problem by adding a second or complementary surface water source to the system.

Castelo de Bode and Tejo options will be examined

According to the official decision dated September 9, the study to be prepared by APA and Águas de Portugal will examine the technical, economic and technical aspects of water supply from Castelo de Bode and/or the Tagus River. and will examine its environmental feasibility.

To the extent possible, the use of existing infrastructure in the north of the Tagus and the establishment of new connection lines when necessary will be evaluated. citeturn1search1

In the study, not only drinking water but also the integration of alternative resources such as reusable water for non-drinkable urban needs will be evaluated.

The new Lisbon airport is also included in the water calculation

One of the striking elements of the plan is the new Luís de Camões Airport.

The government predicts that the new airport, as well as the housing, urbanization, logistics and commercial development expected in the region, will increase water demand in the coming years. For this reason, the system to be established will be planned not only for current problems but also for future population and economic growth. citeturn1search1

Municipalities are also required to reduce water losses

The new water source is not seen as a solution on its own.

The official decision also states that municipalities should make investments to reduce losses in their own networks and increase water use efficiency.

APA and Águas de Portugal need to work with municipalities and other relevant institutions to outline technical alternatives, costs, environmental impacts and implementation schedule.

The work that will be ready at the end of the 120-day period does not directly mean that construction will begin. First of all, which solution is feasible? to be determined; Investment decisions will be shaped in the following stages.

Resources

Diário da República — Despacho n.º 11127/2026, 9 September 2026: Official decision on strengthening the water resilience of Margem Sul

Renascença / Lusa, 9 September 2026: Governo quer solução para falta de água na margem sul em quatro meses