Upon completion of the Legionella Risk Assessment the control program should be adhered to. This is to prevent the infection of individuals with Legionella and subsequently avoid Legionnaire's Disease. This can be done in a number of ways and a quality Legionella risk assessment from Advanced Water Technologies will highlight these in detail and determine which would be the most effective for the particular system in question.
The Legionella bacteria are generally controlled through either chemicals or temperature. Welfare style hot and cold water systems are generally controlled through temperature whilst cooling towers and process systems are normally controlled using chemicals.
It is possible for there to be some overlap and in fact Chlorine Dioxide is an excellent chemical choice for the control of Legionella within welfare style water systems as it can be used safely in drinking water.
In order to manage Legionella using temperature the system should be regularly monitored (at least monthly) to determine that temperature is adequate throughout the system to maintain control.
In general if temperatures of the cold remain below 20° C and hot water remains above 50° C then the system is considered under control, although this is a very simplistic view and many other factors such as the cleanliness of the system and presence of stagnant pipe work can influence the risk.
These temperatures must be recorded and if they fall outside these recommended levels then remedial action should be taken and actions recorded.
Management of Legionella using chemicals requires increased monitoring due to the generally more complex nature of these systems. Chemicals can either be oxidising or non-oxidising biocides and should be dosed on a continual basis, preferably by an automated system that monitors biocide levels constantly.
Biocide dosing rate and maintenance levels will depend upon the biocide species in use but is typically 0.5-2.0 ppm for oxidising biocides. Chemical control of Legionella generally occurs in cooling tower and due to their high risk status it is advisable to employ a specialist chemical water treatment/Legionella control company to help in the management.
All the above points will be included in a full written report with a review meeting to ensure a complete understanding of the results of the risk assessment.
For further information about How we conduct your Legionella Risk Assessment please call us on 01246 813110 or email firstname.lastname@example.org - Alternatively you can complete our online enquiry form.