1. With the global loss of natural wetlands, waterbirds have become increasingly dependent on alternative and artificial habitats, but the use of such wetlands by waterbirds is typically opportunistic and little consideration has been given to the potential implications for water treatment or waterbird conservation objectives.
2. Wastewater treatment wetlands are currently of critical importance for certain waterbird species in some parts of the world, and we illustrate this with an example from south-eastern Australia. Furthermore, we argue that their significance is likely to increase as they offer the most realistic means of treating wastewater in developing countries, where the demand for improved sanitation to lift people out of poverty is intense.
3. There is little scientific evidence to guide the construction of wastewater treatment wetlands with waterbird conservation in mind.
4. The use of wastewater by waterbirds poses health risks for both birds and humans and these risks must be better understood.
5. Synthesis and applications. Wastewater treatment wetlands are not a substitute for natural wetlands and reliance upon them should not compromise wetland conservation efforts. Nonetheless, they are a potentially valuable resource for waterbirds, and research should be directed towards deepening our understanding of their global distribution; food-web dynamics; methods of deterring or excluding birds when bird or human health may be compromised; the effects of wastewater contaminants and pathogens on birds; and the role of waterbirds in human disease transmission.