Bottled water entails an environmental sustainability challenge, and the restaurant industry is a large-scale contributor to this problem as it seems to be reluctant, at least in some countries, to substitute tap water for bottled water. There are two plausible reasons for this; one is that the industry might assume that customers prefer bottled water, mainly because of its taste, and the second is that restaurateurs may be unwilling to forgo the high economic margin from bottled water sales. In this context, filtered water may represent a solution as it is a greener option than bottled water and tastes better than tap water. However, does it represent a satisfying taste option for diners? Moreover, are restaurant consumers willing to pay for filtered water? Given the importance of the answers to these questions, this study proposes to examine whether there are differences between filtered and bottled mineral water regarding their expected and actual taste and customers’ willingness to pay. To this end, this study employed three different experimental groups in an actual fine-dining restaurant in Barcelona. The results show that consumers derive a positive payoff by drinking a more environmentally sustainable option and may even be willing to pay for filtered water. However, there is still room for improvement in filtering systems in regard to the taste of water. These results entail important managerial implications for the restaurant industry since it can become more environmentally sustainable without losing economic profits.