Can I use mineral water as an emergency substitute for coolant?
2 Answers
You can use mineral water as an emergency substitute when you run out of coolant, but you should not add water directly. It should be mixed with coolant before adding. The functions of coolant are: 1. Anti-corrosion; 2. High boiling point; 3. Prevents scale buildup; 4. Anti-freeze. The method for replacing coolant is: 1. Open the car hood after the engine cools down; 2. Open the coolant reservoir cap; 3. Lift the vehicle and open the radiator drain plug, drain the old coolant and reinstall the drain plug; 4. Lower the vehicle and pour new coolant into the reservoir. The full name of coolant is antifreeze coolant, which is a special additive-containing cooling liquid mainly used in liquid-cooled engine cooling systems. It contains: calcium chloride, methanol, ethanol, ethylene glycol, glycerin, etc.
A few years ago, I was driving long-distance when I suddenly noticed the coolant was almost empty. With no shops nearby, I added half a bottle of mineral water as an emergency measure to get to the repair shop. The mechanic said this was a temporary solution but highly risky because mineral water lacks anti-corrosion additives, making it prone to rust and corrode the engine block and radiator under high temperatures. You might not notice any issues in the short term, but over time, it can lead to cooling system blockages, leaks, or even engine overheating and failure. Coolant isn’t just for antifreeze—it also raises the boiling point and prevents scale buildup, which mineral water can’t achieve. After an emergency fix, you must fully flush the system as soon as possible and refill it with dedicated coolant. It’s best to develop a habit of regularly checking fluid levels to avoid similar issues. Keeping a small bottle of OEM coolant in the car is also a safer precaution.
