← Buyer Guides500 PSI Hydrostatic Test, Explained
A hydrostatic test pressurizes the water path (housings, fittings, tubing) with water to 500 PSI — roughly 5× normal operating pressure — and holds it to verify nothing leaks, weeps, or deforms.
Key points
- Normal residential RO systems operate at roughly 40–100 PSI. Testing at 500 PSI proves a large safety margin.
- The test covers the assembled water path: sumps, heads, quick-connects, and tubing runs — not just the housing alone.
- Pass criteria: no visible leaks, no weeping at seals, no permanent deformation after the hold period.
- It is a structural test, not a lifetime predictor — it catches manufacturing defects, not 10-year fatigue.
- Ask for per-lot test records with date, operator, and sample serial numbers — not a generic 'we test everything' claim.
Action checklist
- Confirm the factory has a dedicated hydrostatic rig (ask for a photo/video).
- Agree the sampling plan per lot (e.g., AQL-based sampling at 500 PSI).
- Require records: date, pressure, hold time, operator, serial numbers, result.
- Define failure handling: quarantine the lot, root-cause, re-test after fix.
- For new housings or new suppliers, consider 100% testing on the first order.
Common questions
Why 500 PSI specifically?
It is the industry-conventional proof pressure for residential housings — high enough to expose weak seals and thin spots, standardized enough that every serious factory owns the rig. Some commercial housings test higher; check your housing's rating.
Does passing 500 PSI mean the housing lasts 10 years?
No. It proves the unit was manufactured correctly on that day. Long-term durability depends on material quality, pressure cycling, and water chemistry — separate questions with separate tests.
Related reading
A note on honesty. CWS provides sourcing and QC services for water purification products. This guide is general information for overseas buyers — not a guarantee of any outcome. We don't promise the lowest price in China, and we don't promise zero defects. What we do promise: written inspection criteria, lot traceability, and telling you when something is outside what we can verify.