Health and Safety Executive Overview of Control of Legionella in hot and cold water systems Matthew Hamar HSE - Cardiff
What is Legionellosis? • Collective name for diseases caused by bacteria legionella. • Both pneumonia and non-pneumonia varieties. • The species Legionella pneumophila presents the most serious hazard. • Non pneumonia diseases include pontiac fever-high strike rate with a legionella outbreak
Legionella pneumophila • This pneumonia is fatal in 10-12% of cases. • Incubation period 2-10 days (usually 3-6) • Symptoms include high fever, general malaise, muscle and joint pains, headache, dry unproductive cough, chest pains and respiratory distress • Not everyone exposed will develop symptoms • Some people will not develop the full blown disease and may experience a mild flu like infection • Can be treated effectively using antibiotics
Number of cases of Legionellosis by year of onset of symptoms 2005 to 2014 (E&W)
Number of confirmed cases of Legionnaires' disease by month and year of onset, 2013 – 2015 (E&W)
People at greatest risk • Old and infirm • Men more susceptible than women • Over 45 years of age • Smokers • Alcoholics • Diabetics • Existing respiratory problems • Immuno-suppressed people
Infection route • Inhalation of contaminated water droplets containing the viable bacteria • Water droplets less than 5 microns • No person to person transmission • Not contracted by drinking contaminated water
Where is legionella found? • Legionella is widespread in both natural water sources and artificial water systems. • It multiplies: - where temperatures are between 20-45 0 C; - where nutrients are available; and - where water is stagnant or re-circulates. • Infection can then occur by the inhalation of aerosols or particles generated from the source.
Barrow-in-Furness outbreak • 2500 people affected • 494 clinically diagnosed cases • 180 confirmed • 7 deaths
Legionnaires at Care Home
L8- Legionnaires` disease Foreseeable and Preventable
L8 ACOP describes the responsibilities of employers • Identify and assess risks of legionellosis; • avoid the use of systems that give rise to a foreseeable risk of legionellosis or, where this is not reasonably practicable, prepare a written scheme for minimising the risk from exposure; • implement and manage the scheme of precautions including the appointment of a person, or persons, to take managerial responsibility and to provide supervision; and • keep appropriate records.
Risk Assessment should include: • the management responsibilities and name of the responsible person; • an assessment & comprehensive schematic (where complex) of the system; • details of precautions taken including: - the control method/s – inspection / monitoring and maintenance programme (eg checking the system is kept clean; • records of operation, monitoring and remedial work; • population exposed and risk
Example of a good schematic
Methods of control of legionella in hot and cold water systems • temperature regime; • biocide treatments; • ionisation treatment; • ozone; and • UV treatments
Temperature parameters 70 0 C- rapid kill to 100% 60 0 C -90% killed in 2 minutes 50 0 C -90% killed in 2 hours 45 0 C Bacteria 20 0 C bacteria remains dormant but viable Avoid temperatures in range 20-50 degrees Celsius
Overview of Temp controls Distribute Store cold cold water at water <20 0 C at <20 0 C Note – Hot water should achieve 50 0 C Store hot within 1 minute water & cold should >=60 0 C achieve less than 20 0 C Return within 2 water distribute hot >=50 0 C minutes at water at >=50 0 C sentinel outlets
Sentinel Outlets the nearest and furthest/last outlets from hot and cold water cylinders and tanks .
Dead end and dead legs need to be removed • A dead end- a redundant length of pipe, closed at one end, through which no water is flowing • A dead leg - is a pipe leading to an outlet which water flows but the outlet is un-used or infrequently used. All need to be removed by cutting them back to the main pipe run
Thermostat mixing valves • Picture TMVs these blend hot and cold water to reduce the temperature where a scald risk is present
Expansion vessels in hot or cold water systems (not central heating) • Preferably be flow through design • Have a drain valve – flush through and purge to drain (HSG274 Pt2 Table 2.1) • Minimise volume stored • Should be sited – in cool areas – vertically on pipework not horizontally
Specialised Assisted Baths • Separate cleaning shower head system • Hydro-massage function • Flexible hoses • Expansion vessels • Filters
Other issues to address: • TMVs should be fitted as close as possible to the point of use (typically one per outlet); • Infrequently used outlets should be flushed weekly (includes short usage and no hot water flowing); • Shower heads and hoses should be dismantled, cleaned and descaled or replaced at least quarterly. • Redundant supply pipework should be cut back as far as possible to a common supply; • Replace EPDM (ethylene propylene diene monomer). rubber hoses with eg. PE (polyethylene), PEX (cross-linked polyethylene • Keep water system clean
Monitoring water temperatures for legionella control
Measure the temperature at the hot water tanks monthly • hold the surface probe against the pipe work at the hot water tank outlet • check the temperature tallies with any fixed thermometer, if installed.
Measure the temperatures at the sentinel cold water and hot water outlets monthly Use the immersion probe to measure the temperature of the water flowing from the outlet (NB – on hot outlet where TMV is fitted, this needs to be done on TMV inlet pipe) • Hot water should measure at least 50 0 C within 1 minute of running water • Cold water should measure less than 20 0 C within 2 minutes
Measure sentinel hot water temperature at inlet to TMV monthly Measure at least 50 0 C within 1 minute of running water
Measure the temperatures at the cold water tanks 6 monthly Incoming water Water in tank Measure less than 20 0 C
Common failings 1 • No Legionella risk assessment and occupiers are ignorant of the control and monitoring requirements (lack of competence) • Assessment findings not being implemented • No schematics or not comprehensive • Sentinel outlets not identified • Not measuring hot water temperatures at inlet to TMVs where fitted • Homes only measure and record hot water temps after tmv’s for scald risk • Tmv’s fitted too far from outlet • Not measuring hot water storage temperatures • Hot water storage thermostats set below 50 degrees C
Common failings 2 • No temperature gauges fitted to hot water outlets and returns (and no one measuring with surface probe) • Hot water vent pipe overflowing to cold water tank • Cold water stored above 20 0 C (eg un-insulated cold water tanks located on roofs) • Cold water tank lids not tight fitting or broken • Insects screens not fitted to cold water over flows and vents • Dead legs / ends present • Infrequently used outlets not flushed weekly • No cleaning of shower heads • Evidence that some Water treatment company reports do not reflect the inadequate management, treatment and control of legionella at the homes
When is legionella sampling required? • Where storage and distribution temperatures are reduced from those required • Where an outbreak is suspected or identified • Where assessment identifies it is necessary to help monitor effectiveness of controls
When is disinfection needed? • If required temperatures not being achieved • System has been substantially altered; or • During or following an outbreak
Other issues to consider What is an infrequently used outlet? What is the impact of green technologies or energy conservation on Legionella control? How many people are contracting Legionnaires disease from care homes? RIDDOR does not require non-worker reports of disease to HSE – but requirement to report to HPA
Frequency of Monitoring Frequency of water temperature checks Temperatures Monthly Measure the temperature at the hot and cold water sentinel outlets and the hot water tank Check the temperature at the cold water storage tank/s (at least once in winter Six monthly and once in summer during a hot period); Annually Check a representative number of cold water outlets on a rotational basis
Frequency of other checks The Frequency of Other Checks At least weekly Flush infrequently used hot and cold water outlets At least 3 monthly Clean and de-scale or replace shower heads and hoses Visually inspect the cold water storage tank/s and clean and disinfect as required At least annually Check the schematic diagram/s of the H &CW system to ensure they are correct and up to date (eg addition or removal of water tanks and outlets) Note: All checks should be carried out using safe systems and some checks or corrective actions may need to be done by an external competent person
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