Maintaining a clean water supply is one of the key challenges facing humanity today. Pollution, rising population and climate change are just some of the factors putting increased pressure on our limited water resources. Contamination of the water supply presents a high risk to public health, security and the environment; nevertheless, no adequate real-time methods exist to detect the wide range of potential contaminants. There is a need for rapid, low cost, multi-target systems for water quality monitoring. Information-rich, multivariate techniques such as vibrational spectroscopy have been proposed for this purpose. This review presents developments in the applications of vibrational (NIR, MIR and Raman) spectroscopy to water quality monitoring over the past 20 years, identifies emerging technologies and discusses future challenges.