Water contamination in marine fuels is one of the most common yet underestimated threats to ship reliability. While often dismissed as a minor impurity, water in Very Low Sulphur Fuel Oil (VLSFO), Intermediate Fuel Oil (IFO), or Marine Gas Oil (MGO) can trigger a chain of failures—ranging from poor combustion to catastrophic engine breakdowns.

Even 0.3–0.5% water by mass (the ISO 8217 specification limit) can have outsized effects when entrained as an emulsion or introduced through tank condensation, leaks, or improper handling. At Atlas Lab, we have seen firsthand how water-related fuel failures disrupt voyages, drive unplanned maintenance, and create avoidable financial and reputational losses for operators.

Why Water Contamination Matters

• Loss of Energy Content: Water lowers the effective calorific value of the fuel, reducing efficiency and increasing specific fuel consumption.
• Delayed Ignition & Flame Instability: Water droplets disrupt combustion, leading to incomplete burning, smoke, and carbon deposits.
• Corrosion & Sludge Formation: Water accelerates corrosion in fuel systems and reacts with asphaltenes, creating sludge that clogs filters and separators.
• Engine Damage: Prolonged exposure can lead to injector erosion, liner scuffing, and even catastrophic engine failures.

A 2019 BIMCO survey found that over 25% of reported bunker disputes involved off-spec water content—a statistic that highlights the persistence of this issue despite quality regulations.

When to Test: Critical Moments for Detecting Water

• Bunker Delivery: Independent testing ensures the supplied fuel is within ISO limits before acceptance.
• Tank Condensation Risks: Long lay-ups or humid climates increase the chance of water ingress.
• Pipeline or Barge Contamination: Shared infrastructure is a frequent source of off-spec fuel.
• Post-Separation Monitoring: Even after purification, testing verifies separator efficiency.

Beyond Limits: Ensuring Fuel Quality with Lab Testing

Shipboard “drain checks” or “settling tank observations” are not reliable indicators of water levels. Free water may be visible, but emulsified or chemically bound water is invisible without laboratory testing. Protecting multi-million-dollar marine engines requires laboratory-grade detection and quantification.

Key ASTM / ISO Test Methods for Water in Fuel Oil:

• ASTM D6304 (Karl Fischer Titration): Accurate detection down to 10 ppm, the gold standard for water determination.
• ASTM D 95 / ISO 3733: Determines water by distillation for residual fuels.
• ISO 8217 Compliance Check: Ensures water content is ≤0.5% by mass.
• Centrifuge / Separability Testing: Evaluates the ease of water removal from fuel.

At Atlas Lab, we combine Karl Fischer, density, and FTIR screening for water contamination to provide not just a number, but a clear risk profile of its operational impact.

Conclusion

Water is both the most common and the most controllable contaminant in bunker fuel. Protecting against it requires a proactive, lab-based approach.

Please reach out to us if you have any questions or would like further information about our Water in Bunker Fuel

You can contact our team via phone at +91 9324631646, WhatsApp, or email us at contact@atlaslab.in.