Chlorination is the most often used final drinking water disinfection technique in developed countries. The assessment of water quality and all engineering calculations on disinfection effectivity are based on microbial ability to form colonies on nutrient rich medium. However, it is now widely accepted that many microorganisms when subjected to oligotrophic conditions, e.g. drinking water, can attain a state of non-cultivability, often referred as viable but not culturable (VBNC) when cells retain all their metabolic activity, e.g., respiration, enzymatic activity, but are unable to form visible colonies on nutrient rich media. Thus, the aim of this study was to analyse the disinfection effectivity based on cell ability to divide and metabolic activity. Besides chemical based chlorination, the effect of electrochemical disinfection where active disinfectant is generated from ions naturally found in water was assessed. Batch scale disinfection studies involved various treatment regimes to neutralize faecal indicator organism Escherichia coli. In addition to classical cultivation, cell ability to divide and cell metabolic activity measurements (respiratory activity) were performed. The results of this study showed that irrespective of the treatment method, E. coli first lost its cultivability, then the ability to divide and finally metabolic activity. For chlorination the CT values were more than ten times higher when loss in metabolic activity was assessed. For electrochemical disinfection the results showed that at low current intensity and low chloride ion concentration (0,1 A, 6,8 mg/l), no cultivable E. coli cells were obtained after 15 minutes, whereas less than one log decrease was observed for metabolic activity. Thus, the results showed that the traditional faecal indicator – Escherichia coli which is regarded as very susceptible to chlorination can survive for much longer periods when its metabolic activity, not cultivability is evaluated.