Water quality control in its origin is ensured by collecting water samples from different origins of underground water that EPAL uses (32 operational intakes) for producing water for human consumption as to assess the evolution of untreated water quality, screen eventual anomalous results throughout its collection, treatment, transport, supply, and support of the treatment process.

Underground intakes for producing water for human consumption, which are included in this operational control, are:

• Alenquer Wells
• Ota Wells
• Lezírias Wells
• Valada Wells (they are not used for the production of water for human consumption as a routine, but they are considered for operational control purposes)