Can You Add Water To Coolant? – Yes Or No

Car coolant plays an important role in your long trips. However, many people are unaware of the importance of coolant, so they use water instead of specialized cooling water.

So, can you add water to coolant? What happens when you add water to the coolant? This blog post will answer these questions.

We also show you what causes it and how it can be avoided.

Scroll down for details.

What Is Car Coolant?

Can You Add Water To Coolant

Car coolant is responsible for dissipating heat and cooling, helping the car engine maintain its ideal operating temperature.

It is a compound composed of distilled water, Ethylene Glycol solution, and some substances with anti-corrosion, anti-evaporation, electrolyte reduction, antifreeze, etc.

The antifreeze will increase the boiling point so that the coolant can work effectively in all weather conditions.

Nowadays, some people often add water to the coolant. So can you put water in the antifreeze tank?

Can You Add Water To Coolant?

No. Water contains many minerals that can build up inside a car radiator and cause it to overheat. Worse, it might lead to a deposit in your engine coolant’s cooling system.

Because antifreeze has been mixed into the coolant, you must not add water to the mixture. Otherwise, the coolant will be diluted, and performance will be reduced.

What Are The Consequences Of Mixing Water With Coolant?

adding water to coolant

Let’s discuss some of the effects of adding water to coolant.

Cause the Engine Car To Heat Up

Mixing the coolant with water will cause it to dilute and make the car engine heat up. Today, manufacturers often combine coolant mixtures of water and ethylene glycol in a 1:1 ratio.

Combining an equal amount of water and ethylene is to make an antifreeze liquid.

When adding water to this mixture will destroy the above correct ratio and reduce the antifreeze ability, causing the car engine to overheat.

Lead to Car Engine Corrosion

People have come up with many arguments to determine what causes the engine to corrode.

But, the main factor causing corrosion in car engines is temperature. When the car engine heats up, oxidation will occur and cause rusting of the machinery.

In addition, high-temperature engine corrosion can be caused by increased frictional forces.

As a result, the ethylene glycol in the coolant not only cools the engine but also prevents it from rusting.

Adding some water will dilute this correct coolant mixture and reduce the engine’s resistance to corrosion.

Reduce Radiator Performance

The car radiator has the main role of cooling the engine. Everyone often adds coolant because it helps the radiator to cool the vehicle effectively.

Once water is added to antifreeze, the radiator will be harmed, particularly tap water containing magnesium and calcium minerals.

These minerals will build up in the radiator and reduce its efficiency. Over time, the engine will gradually become hot due to the radiator not working.

If this one continues and you do not detect it in time, it will cause other serious problems.

Destroy the Car Water Pump and Air Coils Prematurely

Tap water includes ions and large inorganic particles, contaminating your car’s cooling system. As a result, they will damage the vehicle’s water pump and air coils.

Is Water A Good Alternative To Coolant?

No. Water cannot be used as a replacement for engine coolant because it cannot bring down the engine temperature.

As the car engine’s temperature rises, the water inside the engine will expand. It will increase volume and crack the engine block.

Besides, regular water will be frozen at 32°F if you don’t use coolant. This will damage the rubber hose, cylinder head, and, eventually, the car engine.

When You Never Use Water as Coolant

We want to remind you to avoid using water as an alternative for the coolant in these cases:

It Should Not Be Used Under Pressure

Car engines often operate at temperatures higher than the boiling point of water.

When you put water in an overheated engine, it will boil and evaporate immediately. This cannot solve the engine cooling problem.

The External Temperature Is Low

The water will be directly affected by the outside temperature.

It can be frozen when the outside temperature drops, causing car engine damage, and the water in the engine will heat up when the outside temperature rises.

Therefore, experts often recommend that people use cooling water instead of water. Coolant compounds will help prevent your vehicle’s engine from freezing.

You Use It Like A Lubricant 

Unlike coolant, water usually does not contain corrosive lubricants. It is not a lubricant and cannot reduce friction in car engines.

Using it instead of coolant will increase the high temperature and pressure inside the car. This accelerates the corrosion process more strongly than ever.

You Apply Water to The Coolant Frequently

After some time, minerals present in tap water will accumulate in the car and lead to engine damage.

Therefore, some experts recommend using coolant to avoid losing money on car repairs.

How Do You Know That You Have Accidentally Mixed Water With Coolant?

Some warning signs that you have accidentally mixed water with a coolant such as:

  • Bubbles: If you see green or blue coolant suddenly foaming up, this is a clear sign that the coolant is no longer usable.
  • Rust: In case the coolant is brown, it is probably rust, and corrosion is in progress.
  • Engine temperature: When the engine temperature rises rapidly, and the vehicle overheats, it means that the car coolant has broken down and cannot be used anymore.

Prevention Tips To Prevent Unintentionally Blending Coolant And Water

Prevention Tips To Prevent Unintentionally Blending Coolant And Water

The car’s cooling system is important in preventing the engine from overheating. The system is filled with coolant, which helps transfer heat away from the engine.

When the coolant is running low, you want to add more water. However, this will have many serious consequences.

Water has a lower boiling point than the coolant, evaporating easily inside the engine. Corrosion and damage to engine parts may result from this.

The heat transfer capacity of water is worse than the coolant. This can cause your car’s engine to overheat.

For these reasons, when your car’s coolant level drops, you must add a sufficient amount of the mixture.

What To Do If The Liquid Is Accidentally Mixed?

Act quickly if you accidentally put some normal water in the coolant reservoir. When the engine temperature is normal, drive to a repair shop and have a technician remove the damaged coolant.

In addition, you should also empty the tank and change the coolant accordingly.

If the engine is too hot, you should move the vehicle to a safe parking spot so as not to endanger other road users.

Next, you turn off the engine and open the hood to let the heat in the engine compartment escape.

Finally, replace the damaged coolant with a new one and take the vehicle to a repair shop as soon as possible.


Can You Mix Distilled Water With Coolant?

No. You should avoid mixing distilled water with coolant. The difference between distilled water and regular water is that it does not contain minerals, which might work.

However, distilled water is not the optimal choice.

What About Bottled Water?

Bottled water may contain minerals, so do not add it to the coolant.

If you still want bottled water, ensure it’s treated well. Otherwise, your car’s engine will be corrupted by the minerals in the bottled water.

Can I Add Deionized Water To the Coolant?

Deionized water will be good for the car engine. Deposits can build up in the radiator and engine cooling system if you use other water sources.

What Type Of Water Can You Mix of Coolant?

The recommended type of water to be added to the coolant is soft water that has been cleaned of impurities and minerals.

Plus, the solution is stoichiometric and ionic balance. This makes the soft water stable, pure, and non-hazardous.


The above article answered the question “can you add water to coolant?” in detail. Coolant and water are important fluids in a car’s cooling system, but you should never mix them.

Adding water will create rust on metal parts and bubbles on the surface of the coolant.

The coolant has broken down and can no longer reduce engine temperature. If you accidentally mix water and coolant, it’s important to act quickly.

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