In this study, we examined behavioural determinants associated with Escherichia coli contamination of drinking water between the point of treatment (PoT) and the point of consumption (PoC) within households (HHs) that were practising household water treatment (HWT) or purchased 20 L bottles of treated water in rural Cambodia. We measured E. coli levels at both the PoT and PoC in 399 HHs in 32 villages in four provinces. The Health Belief Model and the Theory of Reasoned Action guided eight behavioural determinants theorized to be associated with the E. coli contamination. Multivariate analysis was used to build models predicting the E. coli contamination between the PoT and PoC in the HH setting. Behavioural determinants associated with the recontamination of treated drinking water included: perceived susceptibility of treated water to contamination and perception of divine will as a cause of diarrhoea. The perceived susceptibility of treated water to be contaminated was also significantly associated with actual drinking water handling behaviours and practices adopted within HHs, such as how often the drinking vessels are cleaned. We conclude that understanding the behavioural determinants that are associated with the E. coli recontamination between PoT and PoC in the treated drinking water will inform interventions aimed at changing HH behaviours and improving the impact of adopting HWT.