The requirement to achieve adequate Ct for inactivation of waterborne microorganisms in drinking water is only important at the location of primary disinfection installations i.e. locations following treatment where the necessary microbial inactivation of microorganisms in water is affected. At secondary disinfection stations and chlorine booster station located on distribution networks, the achievement of Ct based on downstream contact volume and chlorine concentration is not required. Chlorine is dosed to provide or boost the measurable free chlorine residual in the water for continued verification of microbiological water quality and to prevent contamination in the network. The aim of boosting chlorine in the network should be to ensure that at least 0.1 mg/l free residual chlorine is present at the extremities of the distribution network. Verification of the efficacy of primary disinfection in accordance with Regulation 13(1) of SI 278 of 2007 will ensure that secondary chlorine dosing is needed for residual generation only