I had my engine coolant level at "below LOW" and I was sure there is a leak. So I added 0,5l of tap water (full capacity of coolant is 5l) to check for the leak. It turned out it is not a coolant leak but simply water from AC system.

The question is - what now? Can I drive safely with such a mix up of coolant and a little water?

2 Answers 2


Yes, that should be fine.

I would make sure that the ratio of antifreeze / anticorrosion is correct fairly soon and definitely before winter just in case.

If this is the only time you have done that then it won't hurt. But don't make a habit of it - some engines need the benefits of specific coolant concentrations.


Yes, a bit of water in your coolant shouldn't do any harm. However, A vehicle should not be consuming coolant. So if the coolant level goes down (assuming you do your level checks when the engine is at the same temperature each time (either hot or cold, as the coolant level will change somewhat depending on the temperature of your engine), then you DO have a leak somewhere. It may not be leaking onto the ground, but instead into your oil or cylinders, or might be a small enough leak that it's evaporating before hitting the ground.

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