**1. Introduction**

Water is essential for human life, and the access to safe and sufficient water and sanitation are recognized as basic human rights [1]. Moreover, the United Nations Sustainable Development Goal (SDG) target 6.1 calls for universal and equitable access to safe and affordable drinking water [2]. However, about 2.2 billion people still live without access to safe water, the majority of which are in low- and middle-income countries [3], mainly in sub-Saharan Africa and Asia. In sub-Saharan Africa countries, about 319 million people live without access to improved reliable drinking water sources, and 695 million lack improved sanitation facilities [4].

Each year, 829,000 deaths are attributed to diarrhoeal diseases linked to inadequate WASH, including 297,000 in children under five [3]. Over the coming decades, with a growth rate of about 2.5%, the sub-Saharan region will account for most of the global population growth [5]. This near-future scenario, with densely populated urban and peri-urban areas, entails an increment in water demand and sanitation, pressuring the already compromised WASH infrastructure. The sub-Saharan country of Guinea-Bissau is

**Citation:** Machado, A.; Amorim, E.; Bordalo, A.A. Spatial and Seasonal Drinking Water Quality Assessment in a Sub-Saharan Country (Guinea-Bissau). *Water* **2022**, *14*, 1987. https://doi.org/10.3390/w14131987

Academic Editors: Saurabh Shukla, Jianhua Wu and Peiyue Li

Received: 23 May 2022 Accepted: 20 June 2022 Published: 21 June 2022

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**Copyright:** © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

one of the poorest countries in the world, ranked 175 out of 189 countries on the Human Development Index in 2019. Presently, with a total population of 1,920,922 inhabitants, the life expectancy at birth in Guinea-Bissau is 57 and 62 years for males and females, respectively. Moreover, the under-five mortality rate is 78.47 [6]. According to the WHO [7], in Guinea-Bissau, each person has only 21 L of water for daily personal needs. This value is well under the 50 L minimum known water requirement for human domestic use [8]. The latest data (2016 and 2017) reported that "improved" water sources (not necessarily meaning potable water, but rather a refurbished facility) were accessible to 73% of the population, whereas only 20.5% of the population has access to proper sanitation [9]. The health system is fragile and not universally available, with a very high health burden from malaria, diarrhoea and respiratory diseases, HIV, and malnutrition. Indeed, diarrhoeal diseases are the third leading cause of death, with 702,974 cases reported in Guinea-Bissau in 2019 [10]. Cholera is endemic in the country, being responsible for 71,307 cases and 1638 deaths between 1996 and 2017 [11].

Although a few studies concerning water quality in Guinea-Bissau are available [12–14], these were carried out in limited geographic areas. To the best of our knowledge, no study with broad range has been performed to understand the problem at the national level. However, to design and implement robust measures to ensure safe water for the population, it is pivotal to understand the national status of the water quality, as well as the regional differences. The purpose of this study was to investigate the water quality dynamics across this endemic cholera sub-Saharan country (Guinea-Bissau), and relate it to environmental constrains (including seasonality) and associated WASH components, in order to understand the implications for public health.
