Since the first general elections in 1994, the post-apartheid state has been faced by widespread non-payment of service charges in townships, often interpreted as a ‘culture of non-payment’ held to stem from the anti-apartheid rent boycotts of the 1980s. After the spectacular failure of a campaign to encourage payment for services, and in a context of neoliberal reforms prescribing ‘cost recovery’, many municipalities resorted to the large-scale deployment of prepaid meters, devices that self-disconnect households following non-payment. This article focuses on Operation Gcin'amanzi (Zulu for ‘Save Water’), a controversial large-scale project initiated by the recently corporatised utility, Johannesburg Water, to install prepaid water meters in all Soweto households. Taking this project and the protests against it as a point of departure, I trace the history of prepayment technology in South Africa from its initial development as a depoliticising device in the context of the rent boycotts, to its present deployment in the context of ‘cost recovery’ and neoliberal reforms. While the origins of the meter remain inscribed in the technology, in the post-apartheid period the prepaid meter has been re-rationalised as a pedagogical device ‘aiding’ residents to calculate and economise their water consumption. This entailed creation of what Michel Callon has called ‘spaces of calculability’, forcing especially poor Soweto residents to subject their daily consumption practices to a constant metrological scrutiny. I conclude by suggesting that the history of prepayment is indicative of the larger problematic of citizenship in a context of post-apartheid neoliberal reforms. Inclusion in and connection to the state here becomes contingent upon the successful performance of an ethic that fuses civic duty and entrepreneurial comportment. Simultaneously, the aspiration to bring into being calculative citizens, licenses the recourse to illiberal political techniques.