To what extent should we ensure the explicit inclusion of water quality within the WEF nexus? Discussion of “Water quality : the missing dimension of water in the water–energy–food nexus”*

We congratulate Heal etal. for initiating an important discussion on how to broaden the scope of the water–energy–food nexus. We agree that more explicit inclusion of water quality into the nexus is an important step forward. At the same time, water quality is itself an indicator of e.g. ecosystem services and biodiversity, and improvement of water quality comes with a cost in terms of resource consumption that is typically not included in models studying the water–energy–food nexus. We already see hesitation in using the nexus for policy development, and further complexity may be an additional barrier to its practical implementation. So, while the consideration of water quality is indeed important for the nexus, it also suggests that perhaps it is necessary to consider more local contexts than striving for one global framing for analysis of the water–energy–food nexus.