Sustainable water management for publicly accessible buildings
A TECHNOLOGY BASED ON COMMON SENSE
"It's not rocket science, just common sense", says Mikael Nutsos, inventor of the Zeondas technology.
Zeonda has designed a system that enables continuous circulation all the way out to the tap or mixer, both with hot and cold water.
"Available research shows that it's through both maintained high temperature and circulation that growth of Legionella can be kept at bay", says Mikael. "Thus, the system is designed to do just that."
TECHNICAL PROVISIONS FOR A LEGIONELLA-SAFE SYSTEM
The scientific results are unambiguous. The technical provisions in order to reach the goal of having a Legionella- safe system are few:
- Continuous circulation of both cold and hot water through the entire system, preventing heating of cold water or cooling of hot water.
- No dead legs with stagnant water - anywhere
- Cold water must be kept below 20°C and hot water above 60°C. This prevents growth in the cold water and kills bacteria in the hot water.
Rest
Growth
Decease
The only practically viable way is to maintain water temperature throughout the entire tap water system at minimum 60°C. It was shown that Legionella bacteria in samples from water sources die within hours at 50°C, and even within minutes at 60°C. At 70°C, they perish within seconds.
However, the water supply pipes in our buildings are "coated" after a time of usage by a so-called "biofilm", which are densely packed communities of microorganisms growing on the surface of the pipe. Legionella, protected by such a biofilm, can survive at 70°C for fifteen minutes or more. The same protection is provided when the bacteria colonize amoebas, always present in water from natural sources - or our purification plants. Legionella also survives freezing.
Based on these findings, the Zeonda system not only maintains temperature above 60°C on the hot side, it allows for rinsing the cold side with +60°C water. This way, the system blocks the two drivers for Legionella-growth in tap water systems: stagnant, lukewarm water.
Graph showing Legionella growth at various temperatures.
A SOLUTION RESTING ON SOLID SCIENTIFIC EVIDENCE
A group of scientists at the University of Pittsburgh and at the Vetarans Administration Medical Center in Pittsburgh, USA, studied reports from a large number of sanitization studies. They concluded that there is only one scientifically proven method to keep Legionella growth out of tapwater.
THE CAUSES ARE FEW AND WELL KNOWN
There are a few specific factors in unison that triggers a Legionella break-out. Knowledge is everything when it comes to applying the correct preventive measures and reach the goal of having clean water out of all taps and showers.
Water treatment plants are ineffective
Bacterias are not filtered off by our common municipal water treatment plants, and since Legionella ph. is naturally present in any natural water source, small amounts of the bacteria are brought into our water pipes - every day.
Biofilm covers the inside of our water pipes
If you stick your finger tip into a water pipe you can feel it; a slightly slimy layer on the inside of the pipe. It's a biofilm - a densely packed communities of microorganisms growing on the surface of the pipe. It's in this biofilm that Legionella lives and if the water goes stagnant for a few days and the temperature is right, they flourish.
They grow in still water
Legionella doesn't like flowing water. When it slows down and preferably stops, they flourish. This it's important to keep the water flowing at all times.
Temperature is King
Legionella grows in the temperature range of 20-45°C (see the graphic to the right). At temperatures lower then 20°C, the bacteria stays in resting phase and causes no harm. At temperatures above 45°C, the bacteria perish.
TODAY: DESINFECTION METHODS ARE WIDELY USED, BUT DOESN'T DO THE JOB
Convetional methods for disinfecting tap water systems doesn't provide good enough protection.
Rinsing the entire system manually with really hot water, or adding chlorine, to kill a population of Legionella is only to be done in emergencies. It doesn't do any good even for the near future, as new bacteria are distributed immediately thought the water supply. Since the supply of bacteria is continuous, the demand is for continuous desinfection. A waste of money, environment and staff hours.
The continuous methods widely used today fails due to:
- They cannot disinfect the entire tap water system with maintained effect - the disinfections must be repeated
- They require trained personnel and thorough surveillance
- The installation and operations costs are high
- They are associated with environmental risks and secondary health risks
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