The provision of urban water and wastewater services contributes to greenhouse gas (GHG) emissions. Urban water supply and wastewater utilities can potentially achieve low-carbon or carbon-neutral operation through many “utility opportunities”. Outside the jurisdiction of water utilities, many water-related “wider opportunities” can also contribute to GHG emissions abatement for cities. This study aims to explore the GHG emissions abatement potential, cost effectiveness, and enabling factors of implementing wider opportunities in cities. Using Amsterdam as a case study, we developed a marginal abatement cost curve to compare the abatement potential and cost effectiveness of both utility and wider opportunities. The results show that many wider opportunities related to thermal energy, water end use, and life cycle are cost-effective with significant abatement potential, compared to utility opportunities. This case study and emerging worldwide examples show that the water industry has a role to play to support wider water-related opportunities in cities. This vision can be supported by developing mechanisms to credit utilities for wider opportunity initiatives, building inter- and intrasectoral partnerships for utilities, accounting for scope 3 emissions of utilities, and being open to extend utilities’ role beyond water and wastewater services providers.