Despite efforts to recover quality in rivers and other water bodies, the situation today is that sanitation and wastewater management are issues do not addressed completely due to the lack of political prioritisation that can be translated into poor governance and inadequate O&M; to cultural barriers to accept changes for untreated wastewater disposal in the ecosystem, and to an appropriated knowledge of the real status at different scales. Under these ideas, this paper presents an option to mitigate pollution as result of untreated wastewater disposal into water bodies as rivers or streams associated to the localities where they come from. The study case considered four communities with more than 1000 but less than 10,000 inhabitants, within the Atoyac River Basin, one of the most polluted systems in Mexico due to several point and nonpoint contamination sources. In almost all of communities, the sewage network covered between 40 and 80% combining pluvial water and municipal wastewater. As result of the growing population, the space is compromised to build a treatment facility in some towns. Thus, the proposal considered firstly, the improvement or change of the sewage network system, and then to implement a hydraulic sanitisation system focused in the reuse of the treated wastewater. The system involves the collection, conveyance, treatment and final disposal generating a water quality according to the legislation for irrigation. This could favouring directly to downstream farmers and, indirectly, upstream inhabitants by reducing healthy problems and the problem of an appropriate wastewater disposal. Data used involves satellite imagery and restricted information such as national digital maps for topography, thematic aspects (vegetation, soils) and population and its growing rate.
The result was to install two sewerage river basin pipelines as function of the urbanisation density and space. One collecting 75% of sewage from San Bartolome Matlalohcan town transported to a wastewater treatment plan (WTP) and reused in the same town. Other at the bank of the Atenco River collecting sewage from San Bartolome Matlalohcan (25%), Cerrito de Guadalupe, San Luis Apizaquito and Colonia San Isidro. In the last could be installed a WTP to final disposal at San Miguel Contla for irrigation purposes. Even if the proposal is a good option for these towns to start the sanitisation of their ecosystems due to the limited information available, the sewerage pipe lines need to be implemented by authorities and according to their capability to supply a correct O&M. However, authorities need to pay attention to the inhabitant’s necessities in order to avoid conflicts and to prioritise further actions. Additionally, generate detailed information that allows to carry out a complete hydraulic and hydrological, social and economic analysis is urgent to guarantee the good performance of the actions to be implemented.