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Can I Use Water Instead Of Coolant In An Emergency? Know More Here

Can I Use Water Instead Of Coolant In An Emergency? Know More Here

If you’re in an emergency or short of proper coolant to top up the radiator, you might resort to using regular water instead of the coolant. Right?

According to studies, water is the most common alternative for coolant or antifreeze as it’s called for many car owners in emergencies.

However, car experts might disagree on this. As you’d know, a coolant is primarily for regulating the car’s temperatures in too hot or cold climates.

That is, a coolant’s job is to prevent the engine from overheating and freezing. Surprisingly, regular water isn’t capable of doing so. Read on to know more about this.

Can I use water instead of coolant in an emergency?

Here, the term “emergency” is vital. You can only use water instead of a proper coolant/antifreeze in an emergency.

As a car loses about 60-70% of its energy as heat, you mustn’t use water for more extended periods as water has a low boiling point, and it may start boiling very soon.

Plus, water can also initiate corrosion in the engine. Hence, water can take place in your car’s radiator only in an emergency. And you’d immediately top up the coolant as soon as you feel you can do so.

What happens if you use water instead of coolant?

To understand what happens when you use water instead of coolant, you’d what the latter is in true sense.

Coolant is more or less an antifreeze having a 50:50 proportion of either ethylene glycol or propylene glycol mixed with pure water.

These two coolant elements are responsible for increasing the range of temperatures at which normal water boils or freezes.

That is, normal water usually freezes at 32-degrees Fahrenheit and boils at 212-degrees Fahrenheit. However, a coolant freezes at -35-degrees Fahrenheit and boils at 223-degrees Fahrenheit.

In a nutshell, ethylene glycol or propylene glycol are the two key ingredients that maintain the liquid state of the coolant/antifreeze in such high or low temperatures.

Now, let’s discuss what will happen if you use plain water instead of a radiator’s coolant. You know that the heat generated due to the combustion taking place inside builds up faster in hot climates that can cause severe damages to the engine and other parts like head gasket, cylinder head, etc.

If you’re using water in this situation, it will eventually boil up and evaporate, thus leaving the engine devoid of any coolant.

Similarly, damages like cracks in the radiator, heater core, slanted cylinder head, and a broken engine block are likewise a common sighting in extreme cold conditions when you use water instead of a coolant. If excessively used, water can corrode the engine and different metallic parts in the car’s cooling system.

So, these are a handful of reasons why water isn’t a good choice against a proper coolant or antifreeze in a car.

However, as said above, if a coolant isn’t available and you’re stuck in an emergency, you can use water due to its following advantages as a coolant.

Advantages of using water instead of coolant

The following are the advantages of using water instead of coolant.

  • Since water is available at almost every place, you can top up the water as and when required, only if you’re in an emergency.
  • A coolant is sometimes expensive. So, water is a much cheaper option in front of the coolant.

More than the advantages, there are disadvantages of using water instead of coolant, as discussed below.

Disadvantages of using water instead of coolant

The following are the reasons why you’d not use water instead of coolant.

  • Due to its small range of boiling and freezing temperatures, water will eventually start boiling upon reaching its boiling temperature and evaporate. It will leave the engine without any liquid to cool itself off.
  • Since water freezes at lower temperatures, unlike a coolant, under icy conditions, it’ll quickly turn into solid and cause severe damages to the engine and its parts.
  • Another issue of using water is that as most parts of an engine have metals, water can initiate corrosion.
  • Additionally, water isn’t fully capable of preventing the engine from overheating, no matter in whatever quantity it’s present there. For your information, even a small quantity of a coolant effectively prevents the engine from overheating or freezing.

That’s why to refrain from using water except in an emergency.

How long can you go using water?

According to car experts, you can cover only a little distance with water as a coolant.

Or as your engine starts to heat up, it’ll start using available water at a faster rate, thus leading to its boiling and subsequent evaporation.

Hence, as different engines start to heat up at different miles, there is no distance you can do with water.

Antifreeze Vs. Water

In the previous sections, we talked about why we use coolant and resist using water-based on both advantages and disadvantages.

However, the following three parameters are equally worth knowing about when we talk about antifreeze vs. water.

Boiling Point

Your regular water has a boiling point of around 212-degrees Fahrenheit, while that of the antifreeze is at around 223-degrees. That is, it takes coolant is significantly less likely to boil up and evaporate against water.

Freezing Point

When we talk about the freezing points of water and antifreeze, it’s essential to know that antifreeze has a more great upper hand in front of the water.

That is, regular water freezes at 32-degrees Fahrenheit, while an antifreeze does so at -35-degrees Fahrenheit.


As said initially, antifreeze is nothing but a 50:50 mixture of either ethylene glycol or propylene glycol with water.

These two ingredients prevent the antifreeze from impacting the engine in any way, say corrosion. However, regular water will lead to corrosion in and around the engine’s metal parts if used for longer.

How Do You Fill Up the Radiator?

Modern-day cars are coming up with sealed cooling systems to do with the need to fill up the radiator again and again with coolant.

These eradicate the need to top up the radiator with coolant unless there is a leak, which doesn’t happen often.

How Do you check your radiator fluid?

To check the amount of radiator fluid left, follow the following steps.

  • First and foremost, wear proper heatproof gloves and keep a towel/rag along.
  • Park the car under a shed so that you won’t have to bear the scorching sun rays while checking the fluid contents. It’s a must to allow the engine to cool off before you proceed to the next step.
  • After the engine has cooled down significantly, open the hood and locate your car’s radiator cap. In modern caps, the radiator caps come labeled. You can otherwise refer to the owner manual to locate it in case it is not labeled.
  • Remove the radiator cap, but it can be under pressure at the moment. Hence, place a thick towel or rag over the cap before removing it.
  • Now, you can check the radiator fluid level. If it’s under the danger level, you need to top it up.


Can you use water instead of coolant in the summer?

Ans: No, you cannot use water in the summer. As in summers, the heat build-up skyrockets, the water can quickly boil and evaporate, thus leaving the car short of any liquid. However, water is your last resort in an emergency.

Can I fill my coolant reservoir with water?

Ans: If you have no access to a coolant or antifreeze, it’s better to fill the coolant reservoir with water till you can top it up with quality coolant.


A coolant or antifreeze is an important component of your car. In your car, it controls the engine temperature during varying external temperatures.

For example, if you’re driving in hot conditions, the engine will surely heat up and in this case, the coolant can regulate the overheating to prevent any damage to the engine and its parts.

On the other side, in extremely cold conditions, the engine can freeze. This again can cause damages to the engine and to avoid the same, antifreeze is a must.

Remember, except in emergencies, you should never use water instead of a proper coolant or antifreeze.

To avoid situations without coolant in the car, you should keep a can of the same handy in the car or at home.

As there are different types of car coolants available as per the type of engine, you’d refer to the owner’s manual to know which coolant your car is used to. Generally, car coolants are available in different colors like blue, pink, etc.