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KTW-BWGL risk classes for products in drinking water applications

Drinking water is undeniably one of our most precious resources, yet regulations governing it remain largely national within the European Union.

Efforts are underway to establish a European-wide certification process for products in contact with drinking water. However, in practice, this is still predominantly regulated at the national level.

In Germany, for instance, products are certified based on the KTW-BWGL (published by the German Environment Agency UBA) evaluation criteria. This has recently replaced the Elastomer Guideline, bringing about significant changes in the certification process for product manufacturers.

Understanding P1 to P4 risk categories

Central to this transition are the P1 to P4 risk categories, primarily determined by the size of the product's contact area with drinking water. The limits are given in % of total contact area.

Let's zoom in on risk categories and how they relate to gaskets:

P1 - High Surface Contact ( 10 %): Products in this category, like canisters and pipelines, have extensive contact surfaces with drinking water. The risk of potential material leaching is higher.

P2 - Intermediate Surface Contact (< 10 %): This category includes products with a substantial but not overly extensive contact surface with drinking water. Gaskets often fall into this group. The implications are clear: we must be meticulous when choosing sealing materials to ensure they meet the criteria for P2 certification.

P3 - Low Surface Contact (< 1 %): For products like gaskets, with small or transient contact areas, they might be categorized as P3. While they may not undergo a formulation check, consideration of contact surface size is still essential.

P4 - Minimal Surface Contact (e.g. < 0,1 %): In this category, the contact surface with drinking water is minimal, which can include situations where the contact is very brief. Materials classified under P4 may not require a formulation review.

The challenge with gaskets

In this context it is important to know that gaskets are not clearly regulated at the moment. This means that there is no blanket regulation stating that gaskets must generally be used in risk class P3 or P2.

Here is the tricky part: The risk category for gaskets isn't predetermined by gasket manufacturers since they don't know where they'll be used – in a pump, a pipe, a valve etc. It is the responsibility of the entity installing or certifying the component to determine the risk category. This often involves complex calculations to determine the percentage of contact area between the gasket and the water-exposed surface.


„We recognized the signs early on and thought about it in time to offer our customers a gasket for the drinking water sector that meets all requirements, both technically and in terms of certification.“

Stephan Piringer, Head of Product Development
at KLINGER Dichtungstechnik

KLINGER's P2 solution

With this in mind, KLINGER Dichtungstechnik, focusing on the ease of application and use of our products, has developed the drinking water gasket KLINGERSIL® C-4240 that is approved for the P2 risk category. This certification process includes a formulation review and several product tests. Such a formulation review ensures that only components are used in the product that are included in the positive list of the former Elastomer Guideline and later in the KTW-BWGL.

Products certified for risk category P3, on the other hand, do not require formulation reviews since it is assumed unnecessary. However, when working with gaskets in later stages, users must carefully consider contact areas, leading to cumbersome calculations. This approach may not be the most user-friendly.

KLINGERSIL C-4240 is the comprehensive, user-friendly solution for drinking water applications.

Benefits for users

What does this mean for the user now? KLINGERSIL C-4240 is not only technically outstanding but also aligns seamlessly with the requirements outlined in the KTW-BWGL for use in both, cold and hot water systems within the P2 risk class. So KLINGERSIL C-4240 can be used in situations where the gasket has a relatively high contact area with drinking water. This simplifies the process for end-users, eliminating the need for complex calculations and adjustments.

Contacts mentioned in the article:

» LinkedIn: Stephan Piringer, Head of Product Development at KLINGER Dichtungstechnik

» Tel: +43 2252 62599-154 Email:

Frequently asked questions (FAQ)

Are there specific regulations or guidelines that apply to risk categories P2 and P3 in drinking water applications?
Yes, the KTW-BWGL (evaluation criteria document for plastics and other organic materials in contact with drinking water) guidelines in Germany provide detailed guidance on the certification and use of sealing materials for drinking water. These guidelines specify the different requirements for specific risk categories, including P2 and P3, to ensure compliance and quality standards.

What are KTW-BWGL risk categories P2 and P3?
KTW-BWGL risk categories P2 and P3 are classifications used to assess the suitability of sealing materials for contact with drinking water. They take into account the size of the contact area between the product and drinking water, with category P2 representing a larger contact area (< 10 %) than category P3 (< 1 %).

How does the risk category affect the certification and use of sealing materials in drinking water applications?
The risk category plays a crucial role in determining the suitability of sealing materials for specific applications. Materials classified as risk category P2 or P3 must undergo different testing and certification processes, ensuring they meet the requirements for their intended use.

Why is KLINGERSIL® C-4240 the suitable gasket material for drinking water?
KLINGERSIL C-4240 is certified acc. to the KTW-BWGL for risk category P2 which means you don’t have to worry about extensive calculations or last-minute adjustments. KLINGERSIL C-4240 is engineered to fit seamlessly, providing a hassle-free experience for our clients.

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