Eurotubi Pressfitting NEWSLETTER
 
May 2014  
   
Press fitting system all'MCE

 

Drinking water: Stainless steel, plastic or copper?
From the Marketing Department

We suggest reading an interesting technical study published in 2011 in the magazine "Stainless Steel World". The author is a scholar and professor of metallurgy, particularly expert in the field of corrosion. The article compares the characteristics of stainless steel, copper and plastic related to drinking water piping.

Examining the results of a specific study promoted by the European Commission, Buijs shows how the chemical composition of stainless steel indubitably offers the best hygiene guarantees, making it the best choice for drinking water systems.

Download the PDF of the complete article (English)

Here is a summary of the article:


Use stainless steel to transport drinking water?

For several years there have been discussions on an international level regarding the possibility of replacing copper with stainless steel in drinking water supply pipes. This article pays particular attention to the specific benefits of stainless steel in comparison to copper.


Stainless steel is the best material for conducting drinking water


What is copper?

Copper is a metal that has been considered synonymous with drinking water transport for years.
It is a light and malleable material. It also offers good corrosion resistance.
Nevertheless, it is increasingly criticised because the copper ions released in drinking water could damage human health. An in-depth study was commissioned by the European Commission to determine the quantity of substances emitted into drinking water by various metals and plastic. The results were rather disappointing for copper while they were particularly positive for stainless steel.


Bacteria

Drinking water must not put public health at risk and this risk is directly connected to the presence of bacteria. Bacteria tend to adhere to surfaces where they can create a harmful biofilm. It was discovered that copper surfaces are more predisposed to host them compared to stainless steel even though the contrary was expected given copper's known antibacterial properties. The surface of stainless steel is harder and smoother and thus less "hospitable" to these micro-organisms while the surface of copper promotes bacterial growth.


Plastic materials

Given the harmful effects of copper, there is a growing interest in the use of plastic materials, largely used today, for drinking water piping. As the number of installations increase, plastic pipes show great leakage problems. According to many scholars, plastic pipes can release hazardous phenols in water. This is proven by several studies recently conducted in European laboratories. The concentrations found in pipes that are currently largely used for domestic purposes are high enough to represent a public health problem.


In an article published by the "Legionella Communication Platform" titled "Formation of biofilms and the development of Legionella bacteria in piping", it was shown that in an experimental domestic hot water system (at 37° C), Legionella bacteria (in biofilm) were found in steel, copper and plastic (PE-xa) piping. In the latter, the quantity of biofilm was much more pronounced than in the stainless steel or copper ones.

According to experts, the use of plastics in this type of application is not recommended because they deteriorate much faster than stainless steel. Plus, plastics are treated with additives to prevent the deterioration of the plastic. The additives can become disassociated in a process that released undesired minuscule particles in the drinking water.


Current Situation

The use of stainless steel in this market sector in many countries is still not very common although it is used quite a bit in Switzerland, Italy, Germany and Denmark. There is a growing call for governments to make the use of stainless steel a requirement. This would seem to say that the force of habit reigns and switching from copper to stainless steel would be a huge step.


Stainless Steel 316L for drinking water

If we look at only the economic aspect, it is clear how expensive copper has become. Even stainless steel is not a convenient material and if you take into consideration all of the aspects, the final cost will not be much different. This is especially true if we take into consideration the costs of the negative effects that could be caused by using copper.


Conclusions

Analysis of all of the facts and data will dispel any doubts and contradict any preconceptions that stainless steel would be too difficult and costly for drinking water piping. It is only a matter of time before the quality of this material will be fully realised. In particular, the data regarding public health provide a significant push towards the use of stainless steel.

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