How to Prevent Legionella in Hot Water Cylinders
Legionella (the bacteria that can cause Legionnaires' disease) is rare in the UK.
However, there are still some outbreaks and a major risk factor is bacteria multiplying in stored water.
There are 4 main factors which influence the risk of bacteria developing in water.
These should be taken into account if you want to minimise the risk of Legionella.
Water movement and Legionella Water that remains still for a long time and result in Legionella breeding.
That is why it is important to get correct size of water cylinder for your needs.
While most projects will focus on ensuring that there is hot water on demand, a tank that is too large can result in water stagnating.
A de-statification pump can be fitted to keep the water moving and ensure even temperatures throughout the cylinder - reducing the risk of Legionella.
Water temperature and Legionella You may think that keeping water hot is enough to kill Legionella.
However, it is more complex than that.
The Legionella bacteria is most dangerous in water that is between 20°C and 45°C.
The bacteria is dormant below 20°C, it does not multiply above 50°C and temperatures above 55°C will kill the bacteria.
Most hot water cylinders are set to keep the water higher than 60°C.
While this will kill Legionella, an inefficient cylinder may produce lower temperatures, allowing the bacteria to thrive.
Efficiency of the cylinder Cylinder efficiency has a huge effect of the temperature and movement of the water.
That is why your hot water cylinder should be regularly maintained and that all the connections are cleared.
This will ensure that water is flowing effectively, and kept at the required temperature and pressure.
Materials used in the cylinder The materials used to manufacture the cylinder also have a dramatic influence on the growth of bacteria.
Stainless steel and plastic coils do not stand up to tests in the same way copper coils do.
After 7 days of immersion in water, 80% of stainless steel and 90% of plastic coils were coated in a biofilm.
This is where bacteria begins to form.
Copper coils tested after 7 days showed concentration of E.
coli 100 times lower than stainless steel or plastic.
Copper has a natural ability to kill 99.
9% of bacteria such as Legionella, MRSA and E.
coli within hours.
Tests showed it tool E.
coli 34 days to die on stainless steel, 4 days on brass and just 4 hours on copper.
Using copper rather than alternative materials can help protect against potentially lethal diseases.
So, to reduce the risk of Legionella breeding, keep water moving, keep the water at optimal temperature, use copper rather than other materials and keep the system clean and maintained.
However, there are still some outbreaks and a major risk factor is bacteria multiplying in stored water.
There are 4 main factors which influence the risk of bacteria developing in water.
These should be taken into account if you want to minimise the risk of Legionella.
Water movement and Legionella Water that remains still for a long time and result in Legionella breeding.
That is why it is important to get correct size of water cylinder for your needs.
While most projects will focus on ensuring that there is hot water on demand, a tank that is too large can result in water stagnating.
A de-statification pump can be fitted to keep the water moving and ensure even temperatures throughout the cylinder - reducing the risk of Legionella.
Water temperature and Legionella You may think that keeping water hot is enough to kill Legionella.
However, it is more complex than that.
The Legionella bacteria is most dangerous in water that is between 20°C and 45°C.
The bacteria is dormant below 20°C, it does not multiply above 50°C and temperatures above 55°C will kill the bacteria.
Most hot water cylinders are set to keep the water higher than 60°C.
While this will kill Legionella, an inefficient cylinder may produce lower temperatures, allowing the bacteria to thrive.
Efficiency of the cylinder Cylinder efficiency has a huge effect of the temperature and movement of the water.
That is why your hot water cylinder should be regularly maintained and that all the connections are cleared.
This will ensure that water is flowing effectively, and kept at the required temperature and pressure.
Materials used in the cylinder The materials used to manufacture the cylinder also have a dramatic influence on the growth of bacteria.
Stainless steel and plastic coils do not stand up to tests in the same way copper coils do.
After 7 days of immersion in water, 80% of stainless steel and 90% of plastic coils were coated in a biofilm.
This is where bacteria begins to form.
Copper coils tested after 7 days showed concentration of E.
coli 100 times lower than stainless steel or plastic.
Copper has a natural ability to kill 99.
9% of bacteria such as Legionella, MRSA and E.
coli within hours.
Tests showed it tool E.
coli 34 days to die on stainless steel, 4 days on brass and just 4 hours on copper.
Using copper rather than alternative materials can help protect against potentially lethal diseases.
So, to reduce the risk of Legionella breeding, keep water moving, keep the water at optimal temperature, use copper rather than other materials and keep the system clean and maintained.
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