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 the multiplication of bacteria in stored water.

There are 4 main factors that influence the risk of bacteria growth in water. These must be taken into account if you want to minimize the risk of Legionella.

Water movement and Legionella

Water that remains still for a long time and leads to the reproduction of Legionella. This is why it is important to get the correct size water cylinder for your needs.

While most projects will focus on ensuring hot water is on demand, too large a tank can cause the water to stagnate.

A destabilizing pump can be installed to keep the water moving and ensure uniform temperatures throughout the cylinder, reducing the risk of Legionella.

Water temperature and Legionella

You may think that keeping the water warm is enough to kill Legionella. However, it is more complex than that.

Legionella bacteria are most dangerous in water between 20 ° C and 45 ° C. The bacteria is inactive below 20 ° C, does not multiply above 50 ° C and temperatures above 55 ° C kill bacteria.

Most hot water cylinders are set to keep the water above 60 ° C. While this will kill Legionella, an inefficient cylinder can produce lower temperatures, allowing bacteria to thrive.

Cylinder efficiency

The efficiency of the cylinder has a huge effect on the temperature and movement of the water. That is why your hot water cylinder should receive regular maintenance and that all connections are clear.

This will ensure that the water flows efficiently and is maintained at the required temperature and pressure.

Materials used in the cylinder

The materials used to make the cylinder also have a dramatic influence on the growth of bacteria.

Stainless steel and plastic coils do not withstand testing in the same way as copper coils.

After 7 days of immersion in water, 80% of the stainless steel and 90% of the plastic coils were coated with a biofilm. This is where bacteria start to form.

The copper coils tested after 7 days showed a concentration of E. coli 100 times lower than that of stainless steel or plastic.

Copper has a natural ability to kill 99.9% of bacteria such as Legionella, MRSA, and E. coli in a matter of hours. Tests showed that the E. coli tool dies 34 days on stainless steel, 4 days on brass, and only 4 hours on copper.

Using copper instead of alternative materials can help protect against life-threatening diseases.

Therefore, to reduce the risk of Legionella breeding, keep the water moving, keep the water at an optimal temperature, use copper instead of other materials, and keep the system clean and maintained.