← Buyer GuidesHow to Avoid Leaking Fittings in Your Shipment
Leaks are the #1 field complaint for RO systems — and most originate in quick-connect fittings and O-ring seals, not the housings. Fitting QC is cheap insurance against expensive returns.
Key points
- Quick-connect fittings fail from dimensional tolerance drift, damaged O-rings, or wrong tubing insertion depth.
- The 500 PSI hydrostatic test is the industry-standard gate: pressurize well above operating pressure and hold.
- Vibration in transit loosens marginal connections — packing and palletizing matter as much as the fitting itself.
- Specify fitting brand (or approved equivalents) in the BOM; unbranded fittings are the classic silent substitution.
- A 24-hour standing pressure test on samples catches slow weeps that a quick test misses.
Action checklist
- Lock fitting brand/model in the BOM (no silent substitution).
- Require 500 PSI hydrostatic test records per production lot.
- Pull samples for a 24-hour standing pressure test before shipment.
- Inspect O-rings on incoming fittings: no nicks, no flattening, correct size.
- Verify tubing insertion depth marks are used on the assembly line.
- Check export packing: individual bagging, carton dividers, pallet wrapping against vibration.
Common questions
What is the most common leak point?
In our experience, quick-connect inlet/outlet fittings and housing sump O-rings — both are assembly-quality issues more often than part defects, which is why line audits matter.
Should every unit be pressure-tested, or just samples?
Best practice is 100% testing at a lower pressure on the line plus hydrostatic sampling per lot at 500 PSI. 100% hydrostatic testing on every unit is possible but slower — match the method to your defect tolerance.
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.