By 2030, the global deficit in freshwater resources is projected to reach 40%, in direct correlation with global population growth. To cope with this increase in demand, the Sustainable Development Goals outlined by the United Nations, specifically goal No. 6 of the 2030 agenda, have identified wastewater as a new resource. Indeed, the reuse of wastewater offers three primary advantages: (i) Reused wastewater can serve as an alternative to water from natural reserves, particularly in sensitive geographical areas experiencing water stress. (ii) Wastewater reuse limits the discharge of treated water into the natural environment, which is often a source of pollution, thus helping preserve ecosystems. (iii) Wastewater reuse also facilitates the extraction of valuable compounds, such as fertilisers and precious metals, along with energy generation. This review focuses on various uses of water and the global reuse of treated wastewater from wastewater treatment plants (WWTPs). The focus then shifts to pesticides, exploring the origins of these emerging contaminants and their impacts on aquatic environments. An in-depth analysis of diuron follows, examining its origin, toxicity and regulation and the performance of existing advanced treatments to produce safe water from WWTP effluents.