Wondering which method is best for legionella? You are not alone in this. There is some confusion about what is most efficient, cheapest and easiest to use. My name is Thore Andreassen, I am a master plumber and plumbing engineer and have been in the plumbing industry for 50 years. I have been working with legionella issues since the outbreak in Stavanger in 2007.
So why do I know so much about this? Yes, because I have worked and work with all the methods daily and see in practice what works and what does not work. What is okay and operate and what is not so okay. What to do and what to do. I emphasize that the following are my personal opinions and experiences, and everything I write here can be documented.
To prevent the outbreak of legionella, regular legionella samples should be taken in accordance with the recommendations of the risk assessment in point 1. Note that only legionella culture samples give a correct answer. Stay away from germ counts.
Revision of mapping
Once a year. Change existing survey if changes have been made to the building that affect the risk assessment.
If you have this in order, you can not blame if there is an outbreak, but it is far from good enough. To minimize the chances of legionella outbreaks in a building, it has now become common to install equipment to prevent this. Here you should get my experience on this.
This works well
Copper / silver – must be added copper and silver all the time – good effect – expensive installation – expensive to operate – expensive service agreement – creates problems in the plants by coloring porcelain black and or turquoise, puts copper / silver oxide on autoclaves and ceramic discs – copper / Silver is not broken down in the body and a few are allergic.
Chlorine dioxide – a mixture of chlorine and hydrochloric acid – good effect – must be added all the time – strict requirements for treatment and storage of the chemicals – most affordable and install – expensive service due to strong chemicals that wear on parts – limited how much you can dose that limits effect, especially when the liquid gets hotter – chlorine dioxide can corrode stainless steel in plants.
Anodic oxidation – good effect – separates hydrogen and oxygen in a chamber – no additives -medium installation costs – low operating costs – reasonable service agreement – reliable.
My clear favorite is the anodic oxidation method. No additives to the water, easy to install and in use and reasonable service cost. Decent purchase price.
No facility can guarantee against a legionella outbreak. If a cloud of legionella enters the building via the main water main, these will spread in the plant. It is therefore important to take water samples even if you have a permanent installation. The chance of an outbreak, that the bacteria that have entered is allowed to develop, is much less with such a plant installed than without. We see that when you have facilities, the values quickly go down again. If you do not have one, they go up and can cause a major outbreak.
If you have positive measurements of legionella, it is best to run a chemical cleaning of the pipe system. This is easily done from the water inlet in the building and out to all tapping points. All bacteria are then removed within a few hours. If you leave liquid for a little longer, you also remove all biofilm and other coatings the bacteria live in. Once the bacteria have been removed, you can install a legionella safety system. Some people use chlorine or hypochlorite. This is fine, but it does not remove legionella and the coating the bacteria hides in in a short time. I therefore recommend Termorens for this. Removes the bacteria in less than an hour and all coating in a few hours or overnight.
This does not work well
Hot water flushing. It is tragic to see how many schemes are made to be able to “hot water flush” in facilities. This gives a very bad effect because you usually have far too little water and do not get hot enough water farthest away from the boilers. Even if you have enough hot water, the bacteria are protected by biofilm and the coating they are in and the level increases as soon as hot water rinsing is over. A lot of energy is wasted on wasted work by flushing and energy consumption. With constant repetitions, the piping also wears out due to frequent expansion. Here we have seen and received reports of many leaks that occur during the UV plant process. We have thrown out many of these because they can not keep the bacterial level down. There are two reasons for this. The lamps grow and irradiate more weakly and the water velocity is too high for the UV rays to reach and kill and affect the bacteria enough. Legionella bacteria are robust compared to many others. Some sell plants with UV inside titanium pipes. This does not give a much better effect. The bacteria are said to oxidize, but whether the pipe is made of plastic, steel, stainless steel or titanium, the UV effect is almost the same.
Filter, legionella-free pipes and bends, legionella-free shower heads
Forget it. The problem is more complex than solving anything.
If you need advice and guidance in connection with the design and pricing of legionella systems, contact one of those who have worked a lot with this, and know what they are talking about. Just search online and the “top three” will appear. The most important thing is to take the problem seriously and take action.