According to the WHO, 88% of diarrheal diseases are due to the use of unsafe water, sanitation and hygiene problems. The quality of water depends on the quality of ecosystems and the survival of species. Water pollution therefore has an impact on human health, the survival of ecosystems and an economic cost. For nearly a decade, the distribution of drinking water in Libreville and its surroundings has been disrupted. Many households use rainwater, water from rivers or water from wells to meet daily domestic needs. In order to assess the quality of drinking water resources in Libreville and its surroundings, certain biological and physicochemical parameters are essential. Samples from surface water and wells are shown, pollution of industrial and faecal origin in the waters of the Alinakiri, Ondongo and Ogombie rivers and in the wells of the villages of Kango. In conclusion, the identification of a large number of colonies, staphylococci, clostridium coliforms, the concentration of nitrate and ammonium ions above the values recommended by the WHO confirms this contamination. Water is a component of the environment most vulnerable to various contaminations. Due to the growing demand, the pressure on water resources has now become a global strategic issue. Its management must imperatively be integrated into a political perspective of sustainable development. For this, the protection and safeguard, in the medium and long term, of the quality of this resource is essential.