Drinking Water: A Public Health Issue

The access to safe drinking water is essential to health and a basic human right, as well as a structural part of an effective policy for health protection. (1)

Since 1958, aiming primarily to protect public health, the WHO has published several editions of a document, currently called WHO Guidelines for drinking-water quality, which has been regularly updated through rolling revision. This document establishes the principles and guidelines that are the base for the national programs of the United Nations members. (1)

The model for regulating water quality in Portugal has been progressively consolidated through regular legislation revisions that reflect scientific and technical progress. The consequences have been globally positive and are evidenced in a favourable evolution of the indicator on “safe water”, which builds on the fulfilment of sampling frequency and the observance of parametric values (e.g. microbiological and chemical). Figure 1 shows the evolution of the quality level of drinking water; nowadays 99% of water is guaranteed to be controlled and of good quality (in 1993 this indicator was at a mere 50%). (2) (3) (4)

Fig. 1 – Evolution of the “Safe Water” indicator between 1993 and 2016 (3)

This excellence level is supported by strictly monitoring the stakeholders in this process, among them health authorities that may be integrated in Public Health Units (PHU). (3)

The Activity Plan of the ACeS Alto Ave PHU includes a program of sanitary surveillance for drinking water systems with public distribution. These systems undergo annual characterization as a way to promote risk analysis and management for health. I have recently followed my unit’s environmental health technician on his visits to the drinking water systems in the Fafe area.

These visits started at a Water Treatment Station, where water undergoes a complex treatment process after catchment and is then sent to several reservoirs in the area, which then distribute the water to consumers. Besides verifying the maintenance, hygiene and safety parameters, the process also identifies the treatment types for water (e.g. pre-oxidation, decantation and filtration).

We have then visited all the storage reservoirs in the area where special care is given to the inner lining of tanks/cells, vent protection and latest sanitation date.

Some locations, due to their position and/or demographic rate, benefit from local water capture (e.g. water holes, water springs or wellheads). These Dispersed Systems have their own device for water purification with sodium hypochlorite and sometimes pH correction with caustic soda.

Fig. 2 – Reservoir in Revelhe, Fafe

These visits allow us to promote the conservation and maintenance of several infrastructures of the public water supply systems by the appropriate authorities. But they also allow Public Health physicians (as Health Authorities) to intervene in a stricter and more appropriate way in the case of potential infringements of the chemical or microbiological parameters reported. It may therefore be necessary to establish measures to minimize health hazards to the population. (2)



  1. World Health Organization. Guidelines for drinking-water quality: four edition incorporating first addendum. Geneva, 2017.
  2. República Portuguesa. Diário da República, 1.ª série-N.º 164-27 de Agosto de 2007. Decreto-Lei n.º 306/2007. 2007.
  3. Entidade Reguladora dos Serviços de Águas e Resíduos (ERSAR). Relatório anual dos serviços de águas e resíduos em Portugal – 2017. 2017. Vols. Volume 2 – Controlo da qualidade da água para consumo humano.
  4. República Portuguesa. Diário da República, 1.ª série-N.º 235-7 de dezembro de 2017. Decreto-Lei n.º 152/2017. 2017.


José Miguel Fernandes
Public Health Resident, Public Health Unit ACeS Alto Ave – Fafe