Approach to avoid sanitary risks due to bacterial growth:

1. Minimize time with water temperature above 20 degree C

• Exchange the temperature from water to ambient air as far as possible

• Further cool it down with electric cooler if needed

2. Never let the water be stagnant in tank with temperature above 20 degree C by circulating in the cooling loop.

Legionella temp graf

It is smarter to cool the water 10+ degrees than to heat it 20+.
It is also smarter to cool than to further pollute it with chemicals.