Risk assessment in wastewater recycling and reuse

Wastewater recycling and reuse guidelines and/or regulations have been traditionally and exclusively based on the determination of bacterial indicators and nematode eggs presence. Nevertheless, it has been demonstrated that: (a) virus presence is not well established by bacterial indicators, (b) the viability of nematode eggs is not determined, (c) parasites' presence is not analysed, (d) behaviour of all pathogens once in the recycled water distribution systems and points of use is not known, (e) behaviour of pathogens in the environment is also not known, and (f) chemical risk is not assessed. Additionally, it is to consider that risk associated with reuse is directly related to the final contact host-pathogen, or to chemicals ingestion and contact with the human body. Consequently, future developments of laws, rules and regulations for wastewater recycling and reuse need to include: (a) more detailed biological and chemical analysis of recycled water and environment, (b) the development of tools for determining environmental impact of recycled water and by-products of recycling, (c) the establishment of tools guaranteeing a reduction of the host-pathogen contact, and (d) risk assessment and management mechanisms. Suggestions and recommendations are made on how to include all this items in the future legislative developments for wastewater recycling and reuse.