Water Resistant O-Rings
Compatibility ratings for 7 O-ring materials in Water service
Water is the one fluid where nearly every elastomer performs — six of seven materials rate A in our data. The real selection drivers for water service are therefore temperature and certifications (FDA, NSF 61, WRAS), not chemical survival.
Water (General) compatibility with the seven most common O-ring elastomers, rated on the standard A/B/C/D scale: A = excellent, B = good, C = fair, D = not recommended. This data also appears in our interactive chemical compatibility chart and is available machine-readable at /api/chemicals.json.
| Material | Rating | Guidance |
|---|---|---|
| NBR | A | excellent — recommended for continuous service |
| FKM | A | excellent — recommended for continuous service |
| EPDM | A | excellent — recommended for continuous service |
| VMQ | A | excellent — recommended for continuous service |
| PTFE | A | excellent — recommended for continuous service |
| FFKM | A | excellent — recommended for continuous service |
| HNBR | B | good — suitable for most applications |
Why These Ratings
- NBR (A) — documented strengths include “Water (up to 100C).”
- EPDM (A) — documented strengths include “Hot water and steam.”
- VMQ (A) — documented strengths include “Water and steam.”
- PTFE (A) — documented strengths include “Steam and hot water.”
- FFKM (A) — documented strengths include “Steam (grade dependent).”
GeneralService: Concentration & Temperature Notes
Water looks simple, but the details matter: temperature and certifications (FDA, NSF 61, WRAS) drive selection more than chemical survival. Our seawater row shows the chloride effect — NBR and VMQ drop from A (fresh water) to B while FKM holds A. Hot water and steam are different service entirely; check the steam guidance on the individual material pages.
Recommended
- NBR O-rings (A)
- FKM O-rings (A)
- EPDM O-rings (A)
- VMQ O-rings (A)
- PTFE O-rings (A)
- FFKM O-rings (A)
Use With Caution
- HNBR O-rings (B)
Avoid
No material is rated D for this chemical.
Related Guides
Related Chemicals (General)
Frequently Asked Questions
Is Water compatible with FKM (Viton) O-rings?
FKM is rated A for Water: excellent — recommended for continuous service. Ratings are general guidelines; concentration, temperature and exposure time all affect real-world compatibility, so validate critical applications with ASTM D471 immersion testing.
Is Water compatible with NBR (nitrile) O-rings?
NBR is rated A for Water: excellent — recommended for continuous service. NBR is the lowest-cost elastomer, so when it earns an A or B rating it is usually the economical default; when it rates C or D, do not substitute it for a higher-rated material to save cost.
Can I use PTFE O-rings with Water?
PTFE is rated A for Water: excellent — recommended for continuous service. Remember that PTFE has no elastic memory — in demanding service it needs spring energization or an elastomer core (FEP/PFA encapsulation) to maintain sealing force.
What is the best O-ring material for Water?
NBR, FKM, EPDM, VMQ, PTFE, FFKM are rated A (excellent) for Water in our compatibility data and are the recommended starting point for material selection. Final selection should also account for operating temperature, pressure and whether the seal is static or dynamic.
Can I use EPDM O-rings with Water?
EPDM is rated A for Water: excellent — recommended for continuous service. Always confirm the specific fluid concentration and temperature before specifying EPDM for this service.
Need O-Rings for Water Service?
Send us your fluid, concentration and temperature — our engineers will confirm the right compound. MOQ 1 piece.