Stricter rules must be observed for drinking water applications.
The certification according to UBA [German Federal Environment Agency] for KTW-BWGL has been tightened again in recent years. Germany aims, among other things, to take on a pioneering role in the EU with this. For manufacturers of sealing materials, the certification requirements have therefore increased. “Although the acceptance of the stricter certification in Europe does not look good at the moment, our KTW-BWGL-certified elastomer material for drinking water applications is now available,” emphasize Dr. Birgit Meuret-Hoppner, Senior Chemist, and Bhumesh Sathvara, Rubber Compound Developer at HOLCIM Technical Solutions and Products GmbH, in an interview. Another advantage is its suitability for hot water applications up to 85 °C.
Let’s get straight to a key question: What distinguishes this certification from the previous one?
Dr. Meuret-Hoppner: The new certifications are based on strict testing of the elastomer raw material base and the finished semi-finished product. Manufacturers cannot fall back on old certificates, which was previously possible. The limitation of the certification to five years has not changed.
Why were the approvals tightened?
Dr. Meuret-Hoppner: Germany has taken a pioneering role here, and the aim was to create an approval that would then be adopted by other European countries. In addition, German drinking water fitting manufacturers like Geberit, Wilo, Viega place very high demands on their products and the installed components, such as sealing elements.
But cross-border approval is not yet a reality…
Dr. Meuret-Hoppner: …no, unfortunately not, although that would simplify many things and also reduce the high costs. As is common in Europe, many countries insist on their specific requirements – e.g., what type of water the sealing solution must withstand – and thus on their own approval or additional tests. An example of this is the chlorine depletion test in the ÖNorm B5014-1 [Austrian standard]. The only currently widely recognized standard is FDA conformity, which our materials naturally have. Otherwise, our material has approvals for England (UK) and France, and approval is pending in Austria..
Does this effort then also lead to higher costs, which are subsequently reflected in the product price?
Dr. Meuret-Hoppner: Yes, because the new test costs about twice as much, and recertification is due every five years. This is then quite problematic for price-sensitive sealing solutions in the drinking water sector. Since the drinking water sector in Germany is not a very large market segment, we are also focusing on other European markets to distribute the cost pressure caused by approvals over larger quantities. Our modern manufacturing in Europe for the sheet material, from which the seals are punched, also has a positive effect here.
How does the implementation of KTW-BWGL look from the user side?
Dr. Meuret-Hoppner: Fitting manufacturers and plant operators have always been hesitant in implementing this, which is why there have been repeated deadline extensions. For hoses, the deadline has just been extended again until mid-2026. The challenges here are also greater than for seals. For seals, there is no deadline extension and no reason for one, because the high-performance materials are available.
Elastomer seals were a realized approach in the past. What about TPE and fiber materials?
Dr. Meuret-Hoppner: I can’t comment on that, as we don’t have these materials in our portfolio. Also, the tests are different for each material.
How do you assess the fundamental suitability of TPE as a material for sealing applications in this area?
Dr. Meuret-Hoppner: The material may be interesting for many applications. For sealing applications, it lacks – compared to elastomer materials – the necessary elasticity. A sealing element must remain elastic over its entire service life – at high and low temperatures, under pressure, or under media influence – and exhibit high resilience (restoring force) to seal reliably. And this elasticity of a sealing element is based on elastomers, and the proportion of elastomers is highest in rubber.
Other sealing solutions also have a certification according to UBA for KTW-BWGL – what makes the difference here?
Dr. Meuret-Hoppner: Currently, hardly any materials meet the new requirements – and if they do, then – to my knowledge – only for cold and warm water. Our material is certified for hot water applications up to 85 °C, which significantly expands the range of applications and also allows for standardized use of the material.
Sustainability is also an important topic in sealing technology. How do you assess this in this context? Are bio-based sealing materials approved according to KTW-BWGL conceivable?
Sathvara: They are not only conceivable, but we have already developed them. These materials deliver the same performance as those previously approved. However, we have not yet applied for approval.
Why?
Sathvara: Bio-based materials generally cost more, and therefore, for these price-sensitive sealing solutions, we do not have the corresponding market demand.
This market behavior currently also exists with other bio-based materials. What would need to change?
Sathvara: The topic of “sustainability” would probably need to be more deeply rooted in the mindset of the companies that use these seals. Currently, the focus is on the lowest possible unit price for these seals while complying with current approvals and achieving maximum performance. The argument that all stakeholders could contribute to more sustainability, e.g., through slightly higher seal costs, does not currently resonate. Also, a sustainable sealing element in a drinking water fitting is obviously not a competitive advantage or selling point.
Does such market behavior negatively affect the development of new sealing materials?
Sathvara: No, we have always conducted our development according to foreseeable market trends and customer-specific requirements. We specialize in this with our elastomer sealing materials, which are used not only in drinking water applications but also in the areas of insulating mats, electronics, transformers, and drive motors, e.g., for well-known system manufacturers like SEW. However, we only undertake the complex approvals, which can easily take a year, if we see a corresponding market.
Dr. Birgit Meuret-Hoppner