All water systems in a property should be well built so that they do not cause harm to human health. Several factors should be taken into account at the design stage to prevent microbial growth in systems. These include ensuring the right temperature for the water, sufficient flow and that the water does not remain in the pipes for too long but is run regularly. The condition of water pipes also has an impact, as do pipe materials, water quality and the design of the water systems themselves.
Nowadays, when the price of electricity is on the agenda, one often comes across the desire to reduce the temperature of water systems, especially for hot water. However, this is not advisable under any circumstances. Legionella bacteria multiply between 20 and 50 ˚C, so in most cases a hot water temperature of 55 ˚C is sufficient to kill up to 90% of legionella.
In a thesis carried out at Satakunta University of Applied Sciences, a survey form for Legionella was developed for the health control department of the city of Pori. The study investigated the prevalence of Legionella bacteria in the water systems of ten school properties. Legionella bacteria were found in one of the properties, which was used as a basis for creating an action plan for the health control department of the city of Pori. In general, all the deficiencies found can be addressed by, for example, increasing the temperature of hot water and by running the water regularly.