Can I Use Bottled Water for Coolant?

Coolant is an essential fluid that helps keep your engine cool. This means your car must always have coolant to keep your engine cool and running efficiently. However, you might be driving to an important place one day and realize your engine is extremely hot because your coolant level is extremely low or even empty. 

Ideally, all you need is to top with the correct coolant for your car. But what if you do not have coolant with you and no stores nearby to buy it? Would you run your car that way? You sure know the consequences. However, many people have found themselves in this situation and have been prompted to ask, can I use bottled water for coolant?

can i use bottled water for coolant

Can I use bottled water for coolant?

Yes, you can use bottled water for coolant if your coolant level is low or dry, but only for emergencies. Is it healthy for your radiator? The answer is no; bottled water contains a small amount of calcium that will eventually leave deposits in your engine. However, it is better to have bottled water in your engine than there is low or no fluid at all due to coolant leaking.

Technically, your engine should run on coolant. So while you can use only water in emergencies, it shouldn’t be a norm. And more importantly, ensure you flush your cooling system and fill it with the correct coolant afterward. Remember, bottled water contains minerals that will leave deposits throughout the cooling system and cause engine blockage.

Advantages and disadvantages of using water as coolant

While using water as coolant comes helpful in emergencies, it has its pros and cons. So let’s look at the advantages and disadvantages of using water instead of coolant.


  • Water is inexpensive and easily reachable.
  • It doesn’t contain toxic chemicals that can harm humans, animals, or the environment.
  • Water is a good conductor of heat and can keep your engine running at the correct temperature.
  • You don’t have to wait for your engine to warm up before driving. Your engine is ready for use instantly.
  • You won’t need to open the radiator cap when flushing as there won’t be pressure in the system.
  • You don’t have to buy additional chemicals to add to the water, making it more cost-effective.


  • Water contains minerals that can cause corrosion to any metal that comes in contact with it.
  • Water hardens the seals of your radiator and water pump, which can cause cracks.
  • During the cold months, water can freeze and cause serious damage to your engine. In contrast, coolant contains antifreeze (additives) that ensures water does not freeze, allowing your engine to run smoothly in the cold months.
  • Water boils excessively when the temperature is extremely high; this can boil over other components and cause severe damage. In contrast, antifreeze has a lower boiling which can prevent water from boiling excessively under pressure.
  • Water contains minerals like calcium and magnesium that can lead to the formation of deposits in your radiator and cooling passage when the water evaporates. Hence, causing a blockage eventually leads to overheating, water in exhaust and engine damage.

Can I drive my car without radiator fluid?

Driving a car without coolant and a faulty radiator is a significant problem that can lead to severe consequences for the engine. The coolant in the cooling system is essential as it absorbs heat from the engine and dissipates it through the radiator. Without it, most car engines will overheat within a few minutes of running, depending on factors like ambient temperature, engine load, and condition.

A leak in the cooling system or a faulty coolant pressure cap can cause the coolant level to drop rapidly. The coolant overflow reservoir acts as a buffer, but if it is empty, there is a risk of overheating. Overheating can cause engine components to warp, seize, or suffer other damage that can be costly to repair.

Radiator specialists would advise against running the engine without proper cooling. If you notice a leak or any other problem with the radiator or cooling system, it is crucial to stop driving and pour some water immediately if you do not have any coolant nearby.

When to add coolant to radiator?

You can add coolant to the radiator every two or four weeks, depending on how often you drive and the miles you cover at a go. However, if you check and see that your coolant is low, add coolant to the radiator immediately.


Can I use bottled water to mix with coolant?

Yes, you can mix bottled water with coolant. Generally, coolant is a mixture of water and antifreeze, an additive that helps prevent rust, corrosion, and freezing. So while bottled water contains a small amount of mineral, the antifreeze in the coolant eliminates the mineral when the water comes in contact with the antifreeze.

What type of water do I mix with coolant?

You can add distilled water to coolant, bottled, or tap water. Whatever water you have, once it comes in contact with your coolant containing antifreeze, the antifreeze in the coolant dilutes the minerals inside the water.

If you are only using water as coolant, the best water to use is pure deionized or softened water. While water will never function like coolant, purely deionized or softened water won’t leave deposits in your radiator or cooling system like other water would.

Can you use drinking water as coolant?

You can use any drinking water as a coolant, whether distilled, purified, or even tap water. It is, however, not recommended to leave only water as coolant in your cooling system for a long. This is because most drinking water contains minerals that leave deposits in your engine, hinder circulation and cause blockage over time.

Even if you use deionized or softened water, which won’t leave deposits, water can never function like coolant. For example, while coolant won’t freeze in cold weather, water will. So if you’re using water for coolant, do it only in cases of emergencies and ensure you flush the cooling system afterward before filling it with actual coolant.

water instead of coolant

Can you use water instead of coolant in the summer?

You can use water instead of coolant in the summer months. True, in summer, the chances of water freezing are almost impossible so that coolant won’t be necessary in this case. However, coolant has other functions that water can’t do. For example, if you mix water with antifreeze, you get a coolant. It is this antifreeze that helps prevent corrosion. So you need coolant.

But water alone contains minerals that can cause corrosion. Again, water has a high boiling point. So when exposed to high temperature, it boils excessively and can pour out, touching other components and damaging them. Can water be used as coolant? Yes, but in summary, using water alone will eventually damage your engine.

What happens if you don’t mix water with coolant?

Coolant already is a mixture of water and antifreeze in a 50/50 ratio. So if the coolant for car already has this in the right amount, nothing will happen if you don’t mix water with coolant. So, your car will function well.

If your coolant only has antifreeze, your engine will still get hot and overheat. This is because water and antifreeze, the two liquids used to make coolant, have their functions. Otherwise, coolant will expire soon. While water will cool the engine, the antifreeze will help prevent rust, freezing, etc.

Can I put normal water in my car radiator?

You can put normal water in your radiator as it will allow you to drive your car. However, regular water has very high amounts of minerals left behind as deposits in your radiator once the water evaporates.

These deposits, over time, will clog your cooling system, causing overheating and possible engine damage. While bottled, distilled, or even purified water isn’t free from these minerals, they don’t come in high quantities like regular water. Among those, you can use distilled water in emergencies.

Can you drive your car without coolant in the winter?

No, do not drive your car without coolant in winter. The cooling system is designed to run with coolant, which helps dissipate heat from the engine. So whether winter or summer, your car will still overheat and seize up your engine.


If you have asked, can I use bottled water for coolant? Yes, you can, but it isn’t safe. Bottle water contains minerals that will leave deposits in your engine, mainly if continuously used for a long. However, in emergencies, water can be used as a coolant; it’s better than driving without fluid.

But ensure you flush the cooling system afterward to get rid of any deposit left by the water before filling it with actual coolant. The best water to use as a coolant is pure deionized or softened water, as both are free of any minerals that can form deposits. For those asking, can I use water as coolant? Yes, but know that water alone can never function effectively as a coolant.

Solomon Osuagwu

Osuagwu Solomon is a vetted auto mechanic with over ten years of experience in the garage and five years of experience as a service writer. He prides himself in writing accurate information on professional repair guides, DIY repair guides, buyer’s guides, comparisons, and car reviews. If he’s not in his repair garage, he’s writing automotive blogs to help car owners and fellow mechanics to troubleshoot and proffer solutions to several car problems.

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