1. No Sieve Plate For a bacterial culture to establish, it need to anchor to a suitable surface. This can either be the biofilm left as water cools accross the face of a showerheads, the rubber nipples on traditional anti limescale heads or nooks and recesses in the layers at the face of some heads. The key to the Nordic Shower on this issue is that the only point where a biofilm can grow at the face of the showerhead is on a smooth metal surface which is a fraction of the surface area when compared to the expanse of a most showerheads. Plus metal is not ideal for microbial growth.
2. Nutrition Limescale contains many nutrients such as calcium, manganese, iron and that will settle on certain areas of a showerhead when the water cools - most likely at the face. These layers of deposited materials are termed as biofilm. Biofilm and limescale tends to be remain behind when the water evaporates
. Pooling of water in the reccesses of a sieve plate type head and the final drops from rubber nipples type heads tend to exagerate biofilm build up. As this pooling and cooling /evaporation occurs repeatedly the layers of biofilm deepen, embedding bacteria within - an ideal nutritional for growth and spore formation. Showerheads are especially ideal points in a water system because of this provision of deposition of biofilm here and as most are aerobic - also have access to air. The image here shows a bacterim and a biofilm layer.
3.Moisture Like all organisms water is required for survival and growth. A ideal scenario for growth is a tepid water pool remaining in the head after a shower. Water will pools in a recess of a sieve plate type head and it will sit until it evaporates or the shower is reused in the mentime. This warm tepid pool provides an ideally environement and temperature for microbial growth.
4. Aeration. Aside from the majority of problematic bacterium being aerobic, the most common problem bacteria associated with water systems, Legionnaires, needs to be inhaled so atomization caused by restiction or innner turbulance at the head and an aerated water stream give the ideal conditions for transfer by inhalation. Unlike “aerated”-type flow controls, laminar flow does not draw ambient room air into the water stream, avoiding any possible introduction of airborne bacteria". Peter Jahrling October 1, 2008 issue of Plumbing in Healthcare - Merging Efficiency and Hygiene.
Suggested Remedy - There has not been a showerhead technology invented that can eliminate the health risk posed by microbes and bacteria in water and showerheads - despite any claims otherwise. Reducing the risk by reglarly cleaning any build up on sieve plates by dipping in say a vinegar or anti septic solution is the only feasible measure in a household. But there is one percaution advised. If your showerhead has not had water flowing through it for some time - then bacteria has had an opportunity to multiply and grow because it was not disturbed by water flowing through the showerhead. So if you have not used your shower for a few days - let it run for a minute or so before entering the cubicle to let the flow wash away any bacteria or spores sitting on the surface of a sieve plate biofilm - and you just might escape from picking up that unsuspected holiday bug!
In summary, NordicShower has a unique design and mode of delivery that reduce the suitabality of an environment for pathogen unlike no other - a metal contact area for biofilm ar the exit point, no multi layers or sieve plates and no introduction and thus concentration of airborne bacteria and non aerosoled and large droplets.
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