KTW-BWGL Approval

Author: Oliver Schwing, operations manager, 20 years as head of QA, contact for seals in drinking water applications

What do the abbreviations KTW and WRAS stand for?

KTW stands for Kunststoff-Trinkwasser (plastics in drinking water) and covers plastics, elastomers, thermoplastic elastomers (TPE), coatings and lubricants in direct contact with drinking water. Originally the term only covered plastics; testing under the Elastomer Guideline was added over time. A KTW approval confirms that a material is suitable for contact with drinking water.

WRAS (Water Regulations Approval Scheme) is the corresponding UK approval body for fittings and installations in contact with drinking water. A WRAS approval proves that fittings, pipes and seals comply with the Water Fittings Regulations.

We work with various compound and sheet manufacturers who meet the requirements of the KTW-BWGL and document this with certificates. Feel free to ask us.

Material categories under the KTW-BWGL

Silicones are still covered by the separate KTW guideline and are not part of the BWGL annexes. Check which legal framework applies before every approval. For silicone, usually only a declaration of conformity can be issued.

KTW-BWGL testing procedure

1. Material screening: formulation checked against the positive list of the German Environment Agency (UBA) (Annexes A to E)
2. Type testing and worst-case component: migration test 70 °C × 10 d or 23 °C × 30 d
3. Analysis and limit values: TOC ≤ 2.5 mg/l, individual substances < 0.1 µg/l, sensory 0/3
4. Factory production control: batch release, traceability, QA plans
5. Confirmation of conformity: CoC/DoC including test report and formulation

Which products require KTW-BWGL approval?

Seals and hoses used in drinking water lines and components, e.g. for valves and fittings, pipe fittings and piping systems. Examples of applications are hose rings, O-rings, sealing rings, flat seals, crush seals and moulded parts.

How do products obtain KTW-BWGL approval?

• Sheets and punched parts: EPDM compounds are already KTW-BWGL listed
• Moulded articles: EPDM compounds with KTW-BWGL certificate
• Hoses: extrudate compounds with KTW-BWGL certificate or conformity

Practical tip: test components made from an identical compound together. This saves up to 30 % of the costs.

We developed EPDM blue specifically for drinking water seals. An overview of all applications can be found under drinking water.

Benefits of KTW-BWGL approval for consumers and companies

KTW approval makes a decisive contribution to the safety of all products in the supply chain that come into contact with drinking water or drinking water lines and components.

Key dates

Legally binding since 1 July 2026: the new KTW-BWGL applies to elastomers (Annex D) and TPE (Annex E).

Expected from January 2027: with the EU DWD (EU Drinking Water Directive 2020/2184), uniform European requirements apply to materials in contact with drinking water.

What has changed for seals in drinking water since 1 July 2026 is summarised in our article New KTW-BWGL 2026.