Care Home owners often ask for a guide to legionella testing frequency, there is no single correct answer.
Anyone who contracts Legionnaires’ Disease can suffer from pneumonia-like symptoms. While it can infect many people, not all are affected by this disease. Those who are most vulnerable to its effects include the following:
● the elderly
● heavy smokers
● those with weak immune systems
● those with serious medical conditions such as liver disease or cancer
These bacteria are usually carried by aerosol and transmitted to your lungs. This scenario usually occurs when you’re taking a shower or bath or washing your hands.
Regular legionella testing is a way to ensure the following:
● early detection of the bacteria
● health and well-being of the service users, employees and visitors are protected
● proper documentation of data for legal protection against possible litigation
● avoidance of any potential financial loss such as legal suits or employees getting sick
● collection of data that will support or disapprove the current risk assessment
Legionella bacteria will grow in water with a temperature of between 20°C and 50°C. Above 50°C the bacteria start to become dormant. Above 60°C the bacteria start to be killed off. It is important to keep the entire water system maintained with rarely used outlets flushed weekly, scale deposits removed from showers and taps and TMV’s serviced annually.
Where do you collect the samples?
Usually, you get samples from sentinel outlets for both hot and cold.
● For Hot Water – The first and last taps for EACH storage tank or combi boiler, these are ideal and are called are the Sentinel Outlets
● For Cold Water – The nearest and furthest taps from the storage tank(s) are the sentinel outlets for the cold supply
● Showers – It is good practice to take a sample from your shower(s)
If your furthest tap is fitted with a TMV, do not use this tap to take a hot water legionella sample as the water will be from both the hot and cold supplies – use the nearest direct fed hot tap, i.e. laundry, sluice.
How often should you conduct the tests?
For Hot Water:
There is no legal requirement to test for legionella bacteria however, your Risk Assessment (and Written Scheme of Control) will recommend the best frequency for your particular property depending on the risks highlighted in the report and the control measures you have in place. For most properties, testing every six months is sufficient if you are able to :
● Maintain the stored water temperature at over 60°C at all times
● Achieve a minimum of 50°C (55°C in Healthcare environments) at the furthest outlet of the building within 1 minute of running the tap.
If your water system is unable to achieve the above, more frequent testing is recommended, possibly even WEEKLY.
For Cold Water:
Once again, there is no legal requirement to test for legionella bacteria however if your cold water temperature rises above 20°C there is a risk of legionella bacteria proliferating within the system (especially during the summer months). In this instance, we would advise weekly testing until the water temperature is consistently below 20°C.
If the results are all negative, this means your maintenance, monitoring and control measures are working..
What if the test shows positive for Legionella bacteria?
If the positive result is from the hot water system, the first action should be to pasteurise the system at 70°C for at least an hour then open all taps sequentially to draw the high temperature water through the system. Check to ensure that the water temperature can be maintained – if it starts to drop, wait for the system to re-heat to 70°C and continue flushing. Conduct a retest for legionella bacteria – if the results is still positive,
Whenever there are TMVs (thermostatic mixing valves) it is recommended that the water system is chemically disinfected because the elevated water temperatures will reach the pipework & outlets downstream of the valve. If the positive results are from the cold water, this will require a chemical disinfection.
Finally, if you need Legionella testing kits or just some useful advice, don’t hesitate to contact AquaCert.