How Do You Prevent Water in Your Aircraft Fuel Tanks?

Simple preflight techniques and seal checks can keep the engine running smoothly.

Meg Godlewski

Wednesday, November 04, 2026 at 09:00 AM ET

Verified

Edited By:

Travis Tingle

Aircraft being refueled [Credit: Meg Godlewski]

Key Takeaways:

Prevent water intrusion by ensuring fuel tank seals are intact and fuel caps are securely fastened.
Improve fuel sumping effectiveness by gently shaking wings before inspection, sumping at the end of preflight, and performing multiple sumps after rain or refueling until clean samples are obtained.
Minimize fueling errors by verifying fuel type, using a calibrated pipette post-refueling, and understanding proper fueling procedures.

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Question: A guy at my airport just told me a story about losing power on takeoff in his airplane because there was water in the fuel. We’ve had a lot of rain lately, and his airplane is kept outside. He didn’t get hurt because he had enough runway ahead of him. After the fact, he sumped his tanks again and found water in the fuel. He was surprised, because he sumped the tanks as part of the preflight inspection but didn’t find any water. I keep my airplane outside too, and I’m wondering if there is a surefire way to make sure there’s no water in your tanks other than spending the big bucks for a hangar?

Answer: Wow, glad the loss of power was a nonevent. That’s good training in action.