These works will usually include a drain-down of parts of the system. This often comes with confined space access for personnel to enter large storage vessels, which requires the operatives to not only be trained in disinfection procedures but also safe systems of work and emergency response in the event of collapse or incapacitation within confined spaces.
Typically, these works will also involve working at height in order to access parts of the system located in roof voids and work at high level on the top of large cold water storage tanks. Because of this, additional works may be required to provide safe access, such as boarding-out loft spaces and providing adequate lighting.
Following disinfection works, validation sampling will be required when works are conducted in response to previous high bacterial counts. These samples should be taken no sooner than 48 hours after the disinfection works to ensure that any residual disinfectant in the system does not provide a false representation of the effectiveness of the disinfection.
In systems where high levels of bacterial infection are present, repeated disinfections may be required in order to successfully remove any biofilms that could be harbouring bacteria. Installation of secondary disinfection technologies may be required to provide ongoing system control for the growth of Legionella.