Water Treatment and Plumbing O-Rings
FDA, NSF 61 and WRAS certified EPDM seals for drinking water, wastewater and plumbing systems.
Water treatment and plumbing systems require seals that are safe for potable water, resistant to chloramine and ozone disinfection, and durable over decades of service. The wrong material can impart taste, leach chemicals, or fail prematurely due to biofilm attack. EPDM is the dominant elastomer for water and plumbing seals due to its excellent hot water resistance, low compression set, and compatibility with chlorine, chloramine and ozone water treatments. We supply FDA, NSF 61 and WRAS certified EPDM O-rings for taps, valves, pumps, meters, filtration housings and pipe fittings.
Application Requirements
Design Tips
- 1.Always specify NSF 61 or WRAS grade for direct drinking water contact, not just FDA
- 2.Use 70 Shore A EPDM for the best balance of sealing force and compression set resistance in water
- 3.Design grooves for 15–20% compression to accommodate thermal expansion in hot water service
- 4.Avoid NBR in chloramine-treated municipal water — EPDM lasts significantly longer
- 5.Use black or blue EPDM for UV-exposed outdoor water meters and irrigation valves
Common Sizes
| Size | Typical Use |
|---|---|
| 1/2", 3/4", 1" BSP and NPT fitting seals | standard flat and O-ring profiles |
| AS568-006 to AS568-050 | small tap and valve seals |
| AS568-110 to AS568-178 | pump and filter housing seals |
| AS568-210 to AS568-284 | large valve and flange seals |
Frequently Asked Questions
What is the difference between FDA and NSF 61 certification?
FDA 21 CFR 177.2600 covers food contact materials. NSF 61 specifically tests for safe contact with drinking water, including taste and odor and health effects. For potable water, NSF 61 or WRAS is preferred over FDA alone.
How long do EPDM O-rings last in chlorinated water?
High-quality peroxide-cured EPDM can last 10–20 years in chlorinated municipal water. Sulfur-cured grades may degrade faster, which is why peroxide curing is standard for NSF 61 seals.
Can silicone be used for drinking water seals?
FDA-grade VMQ silicone is acceptable for some drinking water applications, but EPDM is generally preferred for continuous hot water and chloramine resistance in plumbing systems.
Do you supply WRAS-certified O-rings?
Yes. We supply WRAS-approved EPDM O-rings for the UK and EU potable water markets. Certificates and approval numbers are available on request.
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