Seccua Home Solutions

Risks from Water
How many germs are really in my pipes?
Counting bacteria cultures after breading them on a
fertiliser plate, a method going back more than a
century, is still used to detect microorganisms in
drinking water today. A small sample of the water
collected is smeared on a culture medium and the
number of bacteria colonies that form are counted.
Scientists now know that only 0.1 to 1% of all bacteria
in water tend to form colonies on laboratory cultures.
This means
• That for each litre of water we draw from the public
water supply, 100 million bacteria are coming
into the pipes of our buildings.
• Every day, billions of new bacteria thus infect our
pipes.
• The values for Legionella on which we base our
treatments are 100 to 1,000 times below the actual
values. So even if no Legionella shows up in
the analysis, there is still plenty in the actual
supply.
Is heating the water an effective form of disinfection?
Current technical regulations say that the water in
your pipes would need to be heated to 70°C (158 °F)
for at least 20 minutes in order to kill the Legionella
they contain. But scientific studies have shown that
Legionella can survive for more than 60 minutes at
such temperatures.
Our existing technical standards that advise flow
temperatures of at least 60°C (140 °F) and 70°C (158
°F) for thermal disinfection simply no longer meet the
needs for modern environmentally-friendly systems.
Geothermal heat pumps deliver their highest efficiency
at below 50°C (122 °F), while modern boilers
often run with return temperatures at 30°C (86 °F).
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