If I put an immersion heater in my tank & heat the water up to say 40 degrees is there a risk of legionaires disease? The reason I ask is that if warm water is stored between 20 & 50 degrees there's a potential risk of this bacteria growing. Drinking it would be ok but the problem occurs when the water vaporises & is breathed in. It's ideal breeding temperature is about 37.5 degrees hence why it likes our bodies. Or... On the other hand... Because I put my water through the DI vessel & it kills what's in it before it goes in the tank, would it be ok?
As far as I'm aware, the resin in your DI vessel doesn't kill off micro-organisms, it merely removes total dissolved solids in the water like magnesium and calcium. An ultra-violet light is what will do that.
If you read the PDF on the HSE's website under Legionnaires’ disease you will be scared off heating your water in your tank.
However, scanning through it, the importance is on ensuring that your tank is always clean and maintained regularly according to a recorded schedule would definitely be something you should seriously consider.
On the other hand I haven't heard of any Legionnaires disease outbreaks being caused by window cleaners. The most likely outbreaks come from cooling towers and sometimes they are unable to identify the source.
We don't have stagnate water in our tanks unless left for a long duration. The water in our tanks is regularly 'changed' and renewed/replenished. This will also help reduce the risk. Keeping our tanks clean will also remove the microscopic particles that Legionnaires spoor need to grow and multiply. We also don't have any dead ends or hardly used sections in our water systems in the van.
Last summer (2013) was pretty warm for us. I have a blue van and often found the water temperature in the tank was around the 30 degree mark without any form of heating.
In my opinion, were I to use this form of 'heating' I would keep the water below 25 degrees C. But I'm of the opinion that it is better to heat on demand than the whole tank of water. In our case we have a 650 liter tank. Mostly we use 1/2 of it, sometimes 3/4 of it and very occasionally all of it. The tank is always filled each day as we can't predict our water usage for each day. so for me heating 1/2 a tank of water we may not use is a waste of resources.
However, I also realise that others will see this differently. At the end of the day there will still be some warmth in the remaining water. When filling up the water in the tank would still be a little warmer than the water that was used to fill it.
