{"id":4167,"date":"2026-04-09T14:58:54","date_gmt":"2026-04-09T14:58:54","guid":{"rendered":"https:\/\/parmast.com\/?p=4167"},"modified":"2026-04-09T14:58:55","modified_gmt":"2026-04-09T14:58:55","slug":"temperature-maintenance-and-anti-legionella-treatments-on-domestic-hot-water-systems","status":"publish","type":"post","link":"https:\/\/parmast.com\/en\/temperature-maintenance-and-anti-legionella-treatments-on-domestic-hot-water-systems\/","title":{"rendered":"Temperature maintenance and anti-legionella treatments on domestic hot water systems"},"content":{"rendered":"\n

The maintenance of temperature in domestic hot water systems<\/strong> is an issue that concerns not only energy efficiency, but also safety and health. In the water systems of civil and industrial buildings, thermal control<\/strong><\/a> represents the primary line of defense against the proliferation of Legionella<\/strong>, a bacterium that, under certain conditions, can colonize pipes, tanks, and components of the DHW system<\/strong>, with serious consequences for the health of users.<\/p>\n\n

Legionella in water systems: when and why it proliferates<\/h2>\n\n

Legionella<\/strong> pneumophila<\/em><\/strong> survives within a temperature range of 5 to 55\u00b0C<\/strong>, but it is between 20 and 42\u00b0C<\/strong> that it finds ideal conditions to multiply, especially when the inner walls of pipes contain organic deposits<\/strong> (biofilm), limescale buildup<\/strong>, or stagnant areas<\/strong>. Storage tanks, rarely used pipe sections, unused branches, and joints made of porous materials such as rubber are the critical points of any DHW system<\/strong>.<\/p>\n\n

The environments most exposed to bacterial proliferation are large-scale systems<\/strong> and branched water networks<\/strong>: healthcare facilities, hotels, nursing homes, and industrial complexes that use hot water cycles. In these cases, the distance from the heat generation points<\/strong> and the length of the piping<\/strong> make it difficult to maintain uniform temperatures throughout all pipelines, creating potential risk areas.<\/p>\n\n

Temperature maintenance in systems as a preventive measure<\/h2>\n\n

The guidelines<\/strong> for the prevention and control of Legionellosis issued by the Ministry of Health<\/strong>, also incorporated into Legislative Decree 81\/2008<\/strong> for workplace environments, set specific temperature thresholds<\/strong>: domestic hot water must be produced and stored at temperatures above 60\u00b0C<\/strong> and maintained during distribution and recirculation at no lower than 50\u00b0C<\/strong>. Below these limits, the risk of bacterial proliferation increases significantly.<\/p>\n\n

Heat losses<\/strong> in terminal sections, nighttime shutdowns<\/strong>, seasonal variations<\/strong>, and load changes<\/strong> can locally lower the water temperature, even when the generator is operating correctly. Therefore, to ensure stable and compliant conditions throughout the entire network, a dedicated control system<\/strong> and technical solutions<\/strong> specifically designed ad hoc<\/em> to integrate with the system infrastructure<\/strong> are required.<\/p>\n\n

Anti-legionella treatments: types and limitations<\/h3>\n\n

To ensure the prevention of Legionella in water systems<\/strong>, there are two main categories of preventive interventions:<\/p>\n\n