Posted By JohnMackie Paul, Is the L8 not available as a free download from the HSE? now that 01/09 has passed us by. Sorry i couldn't be of more asistance. Perhaps another more informed member could elaborate. cheers

Posted By Jay Joshi L 8 can be accessed at:- http://www.hse.gov.uk/pubns/priced/l8.pdf

Posted By TT Don't know your exact situation but if you know that a building is going to be left 'dormant' for a period of time and then re-occupied, you should really arrange for flushing of all outlets etc. to take place weekly during that dormant period as per L8. Its irrelevant that the building is empty. Letting legionella multiply prior to re-occupation is likely to be frowned upon.... If the building has sat empty for a while and will therefore have stagnating water in the pipes, you're best off assuming legionella proliferation has occurred and to instigate a chlorination/thermal disinfection of the system prior to re-occupation. Aerosol generation during the running of outlets must be minimised - take shower heads/spray tap heads off and disinfect/descale separately etc. Course it still all depends how long its all been stagnating, what water temperatures in the building are etc. Risk assessment on that basis.

Posted By GJB Davis "It is also worth remembering that in ideal conditions, such as if nutrients are present and water temperature is ideal, then the number of legionella bacteria present could have doubled every 12 hours." Legionella cells divide approximately every 30 minutes. Therefore 1 bacterial cell may become 8,388,608 in 12 hours (give or take a few). cheers Giles

Posted By TT If you have reason to suspect a problem may exist then you may want to start earlier...you could have biofilm in certain pipework stretches or in tanks that end up requiring greater attention as they serve to act as a legionella reservoir. A decent biofilm can resist thermal and chemical disinfection and requires extra effort such as biodispersant, mechanical cleaning or in worst cases, replacement of pipework. Perhaps wise to do some sampling in advance to help ascertain the extent of any problem? Advise legionella and TVC as a minimum across a range of outlets.

Posted By TT Happily L8 gives the guidance for you on this one. More than 100 but less than 1000 legionella cfu/l: If one or two samples positive then review control measures, if majority positive then colonisation of system likely and disinfection should be considered. More than 1000: Resample and risk assess to identify further remedial actions necessary (likely an immediate disinfection says TT). You wouldn't normally sample for TVC in a hot/cold water system but if its sat stagnating for a while then it can help to give you an idea of bacterial growth as the water should be supplied to you via the mains as 'fit to drink'. Legionella is not always easy to sample for, even when its there. If you're over 10 to the 4 TVC then you're into needing to take some kind of action territory (were it for a cooling tower). Over 10 to the 6 and you're into immediate disinfection territory. UKAS labs should provide advice on whether the result is satisfactory or not and if you're using a Legionella Control Association accredited contractor to sample then they will also likely advise too.