What gasket material
for drinking water fittings —
approvals and selection
In the UK, WRAS is a widely used voluntary approval route where the project or specification calls for it. German projects may require current product conformity assessed against the applicable KTW-BWGL criteria. TZW and CRECEP appear in other European specifications. FDA 21 CFR 177.2600 is food-contact compliance and may appear in US-referenced specifications — it is not a UK potable-water approval. Material selection starts with the documentation or listing required for the installation country and the service conditions.
Documentation scope: Approval, compliance and certification references apply to the documented material grade, supplier certificate or listing, and stated test conditions unless a product-specific certificate says otherwise. A cut gasket size is not automatically certified as a separate product just because it is made from a documented material. For regulated applications, confirm the current certificate or listing scope, exact grade, medium, temperature, pressure and market requirement before specifying.
Why approval matters — not just material type
A gasket for a heating system connection is selected primarily on temperature, pressure and medium compatibility. For drinking water, an additional requirement applies: the material must not leach substances into the water at levels that would affect its safety, taste or odour.
This is not covered by temperature and pressure ratings. A gasket may be chemically stable, mechanically suitable and correctly sized — and still not be appropriate for potable water contact if it has not been tested and listed under the relevant scheme.
The approval applies to the specific product tested under specific test conditions. It does not extend automatically to all gaskets of the same material type or from the same manufacturer. When specifying for drinking water contact, the approval must be checked for the actual product, not inferred from the material name.
Jurisdiction matters. WRAS is a widely used UK drinking-water approval route where specified. German projects may require current product conformity assessed against the applicable KTW-BWGL criteria. CRECEP may appear in French-market water-contact specifications. FDA 21 CFR 177.2600 is a US food-contact compliance reference, not a potable-water approval. A product documented under one scheme is not automatically documented under another. Confirm which documentation is required for the installation country and application before specifying.
What the approvals cover
WRAS
Water Regulations Approval Scheme — UK reference under the Water Supply (Water Fittings) Regulations 1999 and BS 6920. Tests that the product does not adversely affect water quality under defined test conditions. WRAS approval applies to the tested product or material within the scope, listed conditions and maximum water temperature stated in the approval listing — it should not be extended to every size, thickness or service condition unless the approval documentation covers it. WRAS material approvals are time-limited (typically up to five years) and subject to retest.
KTW / KTW-BWGL
German drinking-water hygiene documentation. "KTW" is the older shorthand installers still recognise; current German documentation should be checked against KTW-BWGL / UBA requirements where applicable. Tests migration of substances from plastic and rubber materials into drinking water. Widely recognised across German-speaking markets and EU industrial applications. Separate from WRAS — likewise concerned with migration under defined test conditions.
FDA
US Food and Drug Administration compliance — specifically 21 CFR 177.2600 for rubber articles intended for repeated food contact (composition and extractives limits). FDA is a food-contact compliance framework, not a UK potable-water approval. It may appear in US-referenced or export specifications; it does not replace WRAS, KTW or other jurisdiction-specific drinking-water references.
TZW / CRECEP
TZW (Technologiezentrum Wasser) is an accredited German testing and research centre that performs water-contact testing and works with certification bodies; a TZW report is not a blanket approval scheme by itself. CRECEP appears in French-market water-contact documentation and should be checked against the exact project requirement. Relevant for specific European market requirements beyond the UK and German standards.
Field check: Before fitting a gasket in a drinking-water line, check the approval document, not just the colour or material name. Look for the exact grade, approval scope, maximum water temperature, installation country and any listed conditions. If the document does not cover that duty, the gasket is not specified for the job.
Kinetics Line materials with drinking-water documentation
The mapped GREENSEAL source cites legacy KTW and FDA 21 CFR 175.300. Those are document references to assess, not current German drinking-water conformity or a UK WRAS listing. Where a UK project specifically requires WRAS, assess REDSEAL PRO 110 or BLUESEAL ULTRA 350 only after confirming the current listing, water-temperature limit and traceability to the supplied grade.
Suitable to assess for potable-water flat face connections within its rated range — including domestic plumbing fittings, water meter joints and general hot and cold water supply duties — only where current product-specific evidence satisfies the actual market requirement. A legacy KTW notation or FDA food-contact citation is not by itself German drinking-water conformity. For a UK specification that requires WRAS, the mapped REDSEAL and BLUESEAL material sources list WRAS references; current listing scope and supplied-grade traceability still have to be confirmed.
The mapped material source lists TZW, CRECEP and WRAS references. That makes REDSEAL a candidate where one of those routes is specified, but it does not prove that every cut size is separately approved. Confirm the current document, its exact scope, maximum water temperature and traceability to the supplied grade.
Temperature ceiling of 110°C continuous limits its use to cold water and lower-temperature hot water supply applications. Not appropriate where connections regularly reach above this limit.
The mapped BLUESEAL material sources list WRAS among their references. For a UK potable-water specification, treat BLUESEAL as a higher-duty candidate only when the current listing scope, maximum water temperature, service conditions and supplied-grade traceability all match. GREENSEAL's mapped source does not list WRAS.
Relevant for higher-pressure water supply connections, hot water systems operating above the GREENSEAL continuous rating, or applications where the aramid fibre construction is specified for its creep resistance under sustained load.
Quick selection table
| Application | Required documentation | Typical material choice | Series |
|---|---|---|---|
| UK cold water supply fitting | WRAS | Vulcanised cellulose | REDSEAL PRO 110 |
| UK potable hot water fitting — below 110°C continuous | WRAS | Vulcanised cellulose | REDSEAL PRO 110 |
| French-market project where CRECEP documentation is specified | Approval per project specification | Vulcanised cellulose | REDSEAL PRO 110 |
| German market — KTW-BWGL / UBA required | KTW-BWGL / UBA | Cellulose + NBR | GREENSEAL PRO 180 |
| US-referenced food-contact specification | FDA 21 CFR 175.300 | Cellulose + NBR | GREENSEAL PRO 180 — verify declaration scope |
| High-pressure water supply — above REDSEAL pressure range, where WRAS scope confirms suitability | WRAS | Aramid + NBR | BLUESEAL ULTRA 350 |
| UK hot water above REDSEAL continuous limit, where WRAS scope confirms suitability | WRAS | Aramid + NBR | BLUESEAL ULTRA 350 |
Documentation references are from product documentation. Always verify current approval status and listing scope before specifying for regulated applications — approvals are subject to renewal, listed conditions and maximum-temperature limits.
The difference between heating water and drinking water gaskets
The same flat face fitting can appear in both a heating circuit and a potable water supply system. The gasket size and mechanical requirements may be identical. The approval requirements are not.
Heating circuit water is typically treated with corrosion inhibitor, is a closed loop and is not consumed. Potable water is consumed directly. The test criteria for potable water approvals assess the effect of the material on water that a person will drink — taste, odour, and potentially harmful substance migration are all part of the test scope.
A gasket documented for heating water contact is not automatically suitable for drinking water contact. GREENSEAL PRO 180 has supplier-sheet references to FDA 21 CFR 175.300 and legacy KTW. For German drinking-water use, obtain current product conformity against the applicable KTW-BWGL criteria; UBA defines the criteria but does not certify products. For a UK specification that requires WRAS, assess REDSEAL or BLUESEAL against the current listing and supplied-grade evidence.
Where a UK potable-water specification requires WRAS, the mapped source references make REDSEAL PRO 110 the lower-temperature candidate and BLUESEAL ULTRA 350 the higher-duty candidate. Neither is selected from the acronym alone: confirm current listing scope, water-temperature limit, service conditions and supplied-grade traceability. GREENSEAL PRO 180 should enter regulated-water selection only when current product-specific evidence covers the market; its supplier-sheet FDA and legacy KTW references do not substitute for WRAS or current German conformity.
For UK drinking water, start with WRAS-listed material. Then select the listed material that matches the approval scope, maximum water temperature, operating conditions and project specification.
The approval determines the starting point. Operating conditions — temperature, pressure — determine which listed material is appropriate for the specific connection. Both criteria apply simultaneously for potable water applications.