Diesel fuel absorbs water. At 82 degrees Fahrenheit, diesel can hold 500 parts per million (PPM) of dissolved water. At 60 degrees, that drops to 50 PPM. When your fuel tank cools overnight, water precipitates out, collecting on the tank bottom where fuel pickup tubes sit.
Water in diesel fuel causes:
- Fuel pump cavitation and failure
- Injector corrosion
- Filter clogging
- Engine seizure
A single water-related fuel system failure costs $3,000-6,000 in repairs.
How to Prevent Fuel Contamination
1. Use Fuel Additives: Diesel fuel additives contain demulsifiers that prevent water from separating from fuel. Using quality fuel from branded stations (Shell, Chevron, Sunoco) minimizes contamination.
2. Install Fuel Water Separators: These systems automatically drain water collected in fuel tanks. Install a secondary separator before your fuel injection pump.
3. Change Fuel Filters on Schedule: Fuel filters trap water droplets. Changing them every 10,000-15,000 miles prevents separator overload.
4. Use Fuel Polishing: Fleet operators use fuel polishing services to remove water and particles from existing fuel supplies.
Conclusion
Water in diesel is invisible until it ruins your fuel system. Use additives, separators, and regular filter changes to eliminate this silent killer.
