Standard & approval
ELL – Elastomer Guideline
Elastomer Guideline, superseded by KTW-BWGL since 1 July 2026
The ELL was Germany's authoritative basis for the hygienic assessment of elastomers in contact with drinking water. Since 1 July 2026, assessment has been carried out under the KTW-BWGL.
Field
Drinking water
Status
superseded since 1 July 2026
Elastomers
Annex D
Testing
Migration & sensory
Overview
The Elastomer Guideline (ELL) was Germany’s authoritative basis for the hygienic assessment of elastomers in contact with drinking water. Since 1 July 2026, assessment has been carried out under the KTW-BWGL.
What does ELL (Elastomer Guideline) stand for?
The Elastomer Guideline governed the selection and testing of elastomers (e.g. EPDM, NBR, FKM/FPM) in contact with drinking water. It defined test media and migration and sensory requirements to protect odour, taste and health.
Which of our products require the assessment?
- Sealing rings/O-rings in valves and fittings, filters
- Moulded articles such as diaphragms, sleeves, sealing lips
- Hoses/hose rings in water-carrying systems
- Flat seals/punched parts made of EPDM, NBR, FKM and others
ELL vs. KTW-BWGL: what applies today?
The former ELL was superseded by the KTW-BWGL on 1 July 2026. For elastomers, Annex D now applies. For TPE (thermoplastic elastomers), Annex E applies; for coatings, Annex B; and for lubricants and auxiliary materials, Annex C. Silicones continue to be assessed under the KTW Guideline for Silicone.
Which requirements are tested?
| Category | Content | Objective |
|---|---|---|
| Migration | Total TOC, specific substances, metals/residual monomers where applicable | Health protection, no undesirable release |
| Sensory | Odour and taste testing under defined conditions | Water remains neutral |
| Material data | Formulation/positive list, hardness (Shore A), density, colourants | Transparent material assessment |
| Component testing | Worst-case geometry, surface/volume, installation scenario | Realistic assessment of the finished sealing element |
| Biofilm | Optional: microbial growth (e.g. to DVGW W 270) | Hygiene in networks/installations |
Test programme and scope (component/material)
- Material screening: comparison of the raw materials with the positive list of the KTW-BWGL (Annex D)
- Risk classification: determine application/temperature/surface-to-volume ratio (risk groups)
- Migration and sensory testing: defined test times/temperatures; TOC, specified substances, odour/taste
- Component testing: type testing on the finished sealing element (e.g. O-ring/flat seal)
- Conformity documents: test report, DoC/CoC, batch traceability (audit-ready)
How do products achieve conformity?
- Preliminary check: review of existing compounds/sheet grades for listability and test history
- Laboratory coordination: test planning with accredited laboratories (material and component tests)
- Series monitoring: production control, material releases, change management
- Documentation: test reports, declaration of conformity, audit file for market surveillance
Benefits for end customers and companies
| Benefit | End users | Manufacturers/OEMs |
|---|---|---|
| Safety | Neutral taste/odour, health protection | Reduced liability and risk |
| Proof | Transparent assessment | Audit-proof documents (DoC/test report) |
| Market access | Suitable materials in the drinking water system | Compliance with legal requirements and tenders |
Practical tips and common mistakes
- Material is not the same as component: a material certificate does not replace component testing.
- Thickness/colour: changes to geometry or colourants can affect the assessment.
- Formulation management: document and reassess every change to the formulation of a rubber compound.
- Think in systems: combined elastomers, plastics and coatings must be compatible (Annexes B to E).
Standards & approvals
Further standards
Cooperation
Seals according to ELL?
Tell us the application, medium and required standard. We will recommend the right material and the appropriate approval.