ᐅ Hygiene storage tank or standard hot water tank?

Hello everyone,

We are currently deciding whether to install a 300L (80 gallons) enamel-coated hot water tank (gas + solar without heating support) or, for an additional cost of about 1700€ gross, a hygienic storage tank in our new build. Since we have a baby, the issue of legionella concerns me a lot. Unfortunately, our customization budget is almost used up, otherwise I would have automatically chosen the hygienic storage tank.

Therefore, I have two questions:

1. How high is the legionella risk if we stick with the standard tank? There is a legionella program that periodically heats the water up to 70°C (158°F), and for safety reasons, I might run the tank at 60°C (140°F). Of course, the question arises about the additional annual energy costs this would cause. Also, I have read that it is suspected that the 70°C (158°F) heating cycle might actually make the legionella bacteria more resistant. Is there any truth to this? I am really unsure.

2. What is the expected service life of both types of tanks, or when would they need to be replaced?

Thanks in advance!

Do you have a gas boiler? If so, simply set the water temperature permanently above 60°C (140°F) to eliminate Legionella bacteria.

However, even below 60°C (140°F), Legionella is generally rare in single-family homes according to various studies. The key is regular water renewal every 2-3 days. In that case, a standard domestic hot water tank is sufficient, and ideally no circulation system, as this can actually promote Legionella growth.

Yes, we have planned a gas boiler plus solar system. Is there a calculator where you can estimate the costs for maintaining a minimum constant temperature of 60°C (140°F) or higher? If the annual costs exceed a certain amount, it might make sense to go for the hygienic storage tank right away, even though the additional costs are painful at the moment.