In 2003–2004, as the Indian city of Chennai faced an unprecedented water crisis, a debate ensued about finding longer-term sustainable solutions, ranging from expensive desalination plants to modest rainwater harvesting schemes. The latter was enforced by an authoritative state and promoted enthusiastically by environmentalists to raise awareness about the city's much-destroyed hydrological ecosystem. In contrast to the state's interpretation reducing it to a compulsory hydraulic installation in individual buildings, environmental NGOs made a concerted effort to develop a more comprehensive intervention in the wider public domain. However, as a dizzying array of socio-political actors came together, concerns emerged about the ability of such a mobilisation to generate a uniform material understanding of rainwater harvesting as a common moral goal. Examining in detail one specific case study of a community-led effort – Puduvellam – this article looks at how, as a grass-roots organisation involved in the restoration of a prominent temple tank in southern Chennai, it rallied support amongst the local (mainly middle-class) residents to create a new topology of ecological consciousness. Its success, however, was only partial and highlights the futility of romanticising rainwater harvesting as an indigenous alternative. More importantly and ironically, its ineffectiveness was enhanced by the crisis itself as it triggered a process of privatisation and commodification of water, with rainwater harvesting eventually being absorbed by the agenda of ‘bourgeois environmentalism’.