Quality Assessment of Three Types of Drinking Water Sources in Guinea-Bissau

Abstract

The lack of access to safe drinking water causes important health problems, mainly in developing countries. In the West African country Guinea-Bissau, waterborne diseases are recognised by WHO as major infectious diseases. This study analysed the microbiological and physicochemical parameters of drinking water in the capital Bissau and its surroundings. Twenty-two sites belonging to different water sources (piped water, tubewells and shallow wells) were surveyed twice a day for three weeks, in both dry and wet seasons. Most of the microbiological parameters were out of the acceptable ranges in all types of water and both seasons and tended to worsen in the wet season. Moreover, in Bissau, the levels of faecal contamination in piped water increased from the holes to the consumer (tap/fountain). Several physicochemical variables showed values out of the internationally accepted ranges. Both well sources showed low-pH water (4.87–5.59), with high nitrite and iron levels in the wet season and high hexavalent chromium concentration in the dry season. The residual chlorine never reached the minimum recommended level in any of the water sources or seasons, suggesting a high risk of contamination. Results reveal a lack of quality in the three water sources analysed, coherent with the high number of diarrheal cases in the country. There is an urgent need to improve sanitarian conditions to reduce the disease burden caused by these waterborne illnesses.

Spatial and Seasonal Drinking Water Quality Assessment in a Sub-Saharan Country (Guinea-Bissau)

“…Overall, similarly to other studies [12][13][14], the chemical contamination was less relevant, with metal concentrations below the acceptable limits for the majority of the studied water sources. Nonetheless, it is important to note that high metal levels were observed in several wells, and the consumption of elevated levels of metals through drinking water has been associated with the development of health problems, including cancer [31].…”

“…Higher levels of contamination were found during the wet season, associated with wells and the use of a bucket to withdraw water. This trend has previously been identified in regional studies performed in the country [12,25].In Guinea-Bissau, the majority of the population retrieve water from shallow (<15 m), hand-dug wells, without any wall isolation or well cover protection. Typically, each well was fitted with a bucket and rope to withdraw water, although some had a manual pump associated.…”

“…The high faecal contamination observed throughout the year is essentially a consequence of the proximity between wells and latrines (<30 m), the presence of freely wandering domestic animals (including cattle), and the contact of the bucket and rope with contaminated soil, as reported by several previous studies in Guinea-Bissau [12][13][14]26] and perceived by the authors in the field.…”

“…The primary source of water to support the daily needs of the majority of the population in Guinea-Bissau, including drinking water, are open/unprotected, shallow hand-dug wells (<15 m). Previous studies reported that about 80% of those water sources were contaminated with faecal materials and had an acidic pH [12,14]. Guinea-Bissau has a tropical climate (hot and humid), with a dry season (DS) spanning from November to May, and a wet season (WS) with high precipitation from June to October.…”

“…Although a few studies concerning water quality in Guinea-Bissau are available [12][13][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.…”