The Cochrane Review on water fluoridation for the prevention of dental caries was published in 2015 and attracted considerable interest and comment, especially in countries with extensive water fluoridation programmes. The Review had two objectives: (i) to evaluate the effects of water fluoridation (artificial or natural) on the prevention of dental caries, and (ii) to evaluate the effects of water fluoridation (artificial or natural) on dental fluorosis. The authors concluded, inter alia, that there was very little contemporary evidence, meeting the Review's inclusion criteria, that evaluated the effectiveness of water fluoridation for the prevention of dental caries. The purpose of this critique is to examine the conduct of the above Review, and to put it into context in the wider body of evidence regarding the effectiveness of water fluoridation. While the overall conclusion that water fluoridation is effective in caries prevention agrees with previous reviews, many important public health questions could not be answered by the Review because of the restrictive criteria used to judge adequacy of study design and risk of bias. The potential benefits of using wider criteria in order to achieve a fuller understanding of the effectiveness of water fluoridation are discussed.