Skip to main content
RISE logo

Legionella safe & energy efficient domestic hot water with limited water volume

Optimization of energy use is central for sustainable development. A contributing factor for optimization is the temperature of the domestic hot water. It is a compromise between energy use and microbial safety. The project studies a limited water volume solution that allows the water temperature to be reduced without increasing Legionella risk.

Aim and goal

This project aims at evaluating how a limited domestic hot water (DHW) volume at reduced temperature will affect the growth of Legionella and how such a system could be implemented in real buildings.


One important aspect in sustainable building is to optimize energy consumption, with DHW temperature being one essential factor. The optimal DHW temperature is often a balance between energy demands and microbial safety, in particular the risk of Legionella spp. at temperatures below 50 °C. Methods to remove Legionella used today has been shown to last for a short time and give rise to e.g. problems with leakage due to damage on the DHW installations. There is therefore a need to investigate novel approaches to solve this problem.


In new building constructions and renewal projects it is important to design the DHW system correct to minimize energy consumption and lower the risk of Legionella. One such approach would be to use a small volume of DHW, e.g. 3 L, and to heat the water instantaneously when needed. This approach has been tested in Germany and Denmark, but further evaluations are needed under Swedish conditions. There is also a need to study the Legionella biofilm formation under controlled conditions in such a system to be able to assess the risks in a long-term perspective.


The investigated system could potentially provide a stronger Legionella protection, and simultaneously allow a reduction of the DHW temperature with substantial reduction in the energy consumption.


Project name

Legionella safe domestic hot water




Infection control, Microbiological safety, Water

RISE role in project

Project manager

Project start


2,5 år


Lund University, 19 partners representing technology suppliers, energy companies, consultants


Formas, Project information in Formas project database

The UN sustainable development goals

Good health and well-being
Clean water and sanitation
Industry, innovation and infrastructure
Sustainable cities and communities

Project members

Charlotta Löfström

Contact person

Charlotta Löfström


+46 10 516 67 30

Read more about Charlotta




How much clean, drinkable water have you used today? No doubt we all regularly turn on the tap without giving it a thought. However, in many parts of the world, clean water is a luxury. Every year, children and adults become ill a…

Built environments

The cities and communities of the future are sustainable and vibrant. They have smart integrated systems for mobility, water, energy and materials. In smart cities waste is considered to be a resource, and is reused or recycled. R…

Infection control

Around 700,000 people die every year as a result of infections caused by resistant microorganisms. According to the World Health Organisation, antibiotic resistance poses one of the greatest threats to our health. Rapid developmen…


Consumers and society are placing increasing demands for a future in which food is both sustainably and ethically produced and at the same time has a positive impact on health. Together with our customers and partners, we are deve…

Microbiological safety

In the West, one in six people suffer from food poisoning each year. Approximately one in every ten people admitted to Swedish hospitals are suffering from foodborne microbial infections. The costs to businesses and society as a w…

Preventative healthcare

The field of preventative healthcare gathers researchers, social stakeholders and the private sector in research and innovation projects aimed at preventing illness from all perspectives; people, systems, policy and technology. Ac…