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Water Quality


EPAL supplies water to around three million people. It is responsible for distribution in the City of Lisbon, to approximately 350 thousand customers, and a further 34 Municipalities, ensuring the supply of quality water to all.

The water is extracted from surface water sources, in River Zêzere – Castelo do Bode Reservoir and in River Tejo – Valada Tejo, and from groundwater sources in Alenquer, Lezírias and Ota.

Water treatment
The water extracted from Castelo do Bode reservoir is treated in Asseiceira WTP and the water extracted from Valada Tejo is treated at Vale da Pedra WTP. The water extracted by EPAL from groundwater sources is disinfected by the addition of chlorine.

Chlorine is used safely and effectively in the disinfection of water for human consumption, ensuring its microbiological quality throughout its journey from the water treatment plant to the building network. Chlorine levels are controlled and monitored 24 hours a day, with levels being adjusted whenever necessary.

Water Quality Control
EPAL analyses and controls the quality of the water extracted, transported and supplied on a daily basis. This control is carried out through continuous monitoring equipment installed at strategic points in the supply system, as well as through laboratory analyses carried out by qualified technicians using advanced technology.

Annually, EPAL carries out more than 300 thousand analyses in the control of water quality, achieving over 99% compliance with National and European legal requirements. 

The results of laboratory analyses carried out by EPAL in compliance with the legislation in force are available at Communication of Water Quality data.

If you want to know about the quality of the water distributed where you are and how to find the drinking fountains in the city of Lisbon, use the free App “H2O Quality”.

Find out more about EPAL’s Water Treatment and Control and clarify your doubts at:


The quality of the water supplied to the customer at the entry to the building may change due to a lack of maintenance/hygiene in the building network and fittings, especially if the pipes are old or made of cast-iron, or after temporary absences.

The customer/owner is responsible for the building network and must ensure its good state of repair and maintenance. 

Find out about EPAL's recommendations at:


Water is essential to life, so it's important to stay well hydrated every day. 

Check out the information about staying hydrated and some very simple tips for drinking more water and with greater satisfaction.

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