← Technology Wiki500 PSI Hydrostatic Pressure Test
A hydrostatic test pressurizes a water-contact component with water (not air) to a multiple of its rated pressure — CWS tests every water-holding unit to 500 PSI to catch leaks and weak seals before shipment.
How it works
- The unit is filled with water, all air is bled out, and pressure is raised to the test level and held.
- Water is used (not air) because it is nearly incompressible — a failure releases far less energy.
- Test pressure is a multiple of rated working pressure (e.g., 500 PSI test vs ~90 PSI working pressure).
- Any pressure drop, weep, or deformation during the hold period is a fail.
Key specifications
| CWS test pressure | 500 PSI |
| Typical working pressure | ~60–90 PSI |
| Safety multiple | ≈5–8× working pressure |
| Medium | Water (hydrostatic) |
What buyers and QC should check
- Ask whether the test is per-unit (100%) or sampling-based — the defect escape rate differs enormously.
- Request the test record format: a credible supplier logs pressure, hold time, and pass/fail per serial/batch.
- For housings and fittings, hydrostatic testing matters more than any marketing claim about 'high quality'.
Free one-page QC checklist (PDF)
The buyer checks from this entry, condensed for the factory floor or the inspection. No signup needed.
Download free PDF checklistCommon questions
Why test with water instead of air?
Safety and sensitivity. Water barely compresses, so a failure is a drip, not an explosion — and even tiny leaks show as pressure drops.
Is 500 PSI overkill for a home water filter?
That is the point. Home line pressure is 60–90 PSI; testing to 500 PSI proves the safety margin. A unit that survives 500 PSI will not burst in a kitchen.
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