© 2020, Springer Nature Switzerland AG. The United Nations has called for increased public participation in scientific research, to benefit professionals, the public and the planet. Citizen science has been suggested as a cost-effective means by which this call can be met, and by which monitoring for the Sustainable Development Goals (SDGs) may be carried out. Indeed, citizen science has gained significant attention in recent years as the scale of environmental issues surpasses the monitoring resources that currently exist. However, many challenges continue to act as a barrier to the acceptance of citizen science as a reliable scientific approach. Here, the current state of knowledge on the use of citizen science in water quality monitoring is reviewed, and the potential for utilizing this approach to enhance monitoring for SDG Indicator 6.3.2 on the “proportion of bodies of water of good ambient water quality” is evaluated. The objective of this review is to identify key knowledge gaps and hurdles hindering the adoption of citizen science contributions to water quality monitoring under the SDGs, so that these gaps may be addressed in a timely manner for future monitoring programmes.