Can You Use Water As Coolant?

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If you’ve ever put water in your coolant tank, you’re not the only one. A lot of people believe that using water as a substitute for coolant is perfectly okay.

If you frequently experience hot weather, you may think that antifreeze is pointless. The truth, however, is completely different, especially if you live in a hot climate.

Water may be more affordable, but using it as coolant could make your car’s engine run hotter and wear out faster than normal. If you own a car, coolant is a necessity.

We’ll cover this in more detail below, including how antifreeze works and why it is so important. Keep reading to learn more about why you should never use water as a coolant.

What Does Coolant Do?

Coolant, also known as antifreeze, is a substance mixed with water to extend the range at which water boils or freezes.

Water tends to boil at 212°F and freezes at 32°F. When water is mixed with antifreeze at a 50/50 ratio, its boiling point increases to 223°F, while its freezing point rises to -35°F.

The active ingredients in the coolant are propylene glycol or ethylene glycol.

These let the coolant/water solution stay in its liquid form, even when it’s subject to intense temperatures.

Can You Use Water As Coolant

Antifreeze also contains inhibitors and additives that prevent engine parts from corroding.

Your coolant will also contain dyes that give it a distinct shade. Whether it’s blue, pink, orange, or green, the color helps people decide which product is best for their car.

If there is a leak, the dye also helps people identify which system is affected. Coolant will be a vivid shade, but oil will be black washer fluid blue, and brake fluid clear.

How Coolant Works

When you start your vehicle, the temperature inside the engine is around 200°F. This is a lot of heat, so the engine needs to keep cool to prevent it from breaking down.

As you drive, the temperature rises until it reaches the boiling point of water (212°F).

At this point, the vehicle’s cooling system directs the coolant flow through the engine and cylinders. The coolant also takes in heat from the engine during this process.

This heated solution flows to the radiator, then is cooled by air that enters the engine bay.

The radiator also has a fan that cools the radiator down. This fluid is now cool, and can then flow back to the engine to take in more heat.

The water pump also manages coolant as it flows through the cooling system.

An overheating car may be the result of a water pump failure, a leaking hose, or a faulty thermostat.

Why Coolant Is So Important

The heat produced from internal combustion can build up quickly. These high temperatures can be intense enough to harm the engine, blow the head gasket, or warp the cylinder.

Using water in the place of coolant won’t stop the water from boiling.

As it flows through the cooling system, the extreme temperatures will boil the water and make it evaporate. The car will then have no coolant running through it.

This is also the case in cold conditions.

Water may freeze inside the engine, resulting in cracks in the heater core, engine block, and radiator. The cold may also be intense enough to warp the cylinder head.

This is why coolant is so important. Coolant will help keep the fluid in a liquid state, no matter what the temperature is.

Using coolant will keep the car running efficiently and increase its lifespan.

Advice On Using Coolant

Before you start mixing your coolant with water, make sure that you do so with pure, distilled water.

Regular water from the tap will have minerals that can accumulate inside the cooling system and radiator. This can start to build up and obstruct the coolant from flowing freely through the engine.

Can You Use Water As Coolant?

As you would with other car fluids, keep checking your car’s coolant. You should make sure that you have enough in the system and that it’s free from leaks.

The metals in every cooling system will differ with each car.

Some manufacturers will have created a coolant designed to work with their system, depending on the exact materials used in their engine and gasket.

Some research teams have even produced a liquid that won’t break down the components and alloys. This allows the fluid to perform efficiently in systems that are placed under pressure.

This is why you should always research which types of coolants are better for your car. Using the wrong product can damage your vehicle.

The liquid may corrode metals and harm any system it flows through. These include the radiator, radiator hoses, cylinder gasket, and water pump.

Remember, some coolants may state that they are suitable for all vehicles, but you should always confirm this with your car’s manufacturer.

Coolant Warnings

Coolant made from ethylene glycol is toxic to humans, pets, and wild animals, even in tiny amounts.

Ethylene glycol is thick and sweet, but it doesn’t have a color or odor. Just a teaspoon is enough to kill a cat, while two tablespoons can severely harm children.

If you have pets and young children, you may want to opt for propylene glycol coolants instead. This coolant is toxic, but only in larger amounts.

You should also avoid pouring antifreeze down the drain. It tastes sweet, so animals that frequent sewer openings may ingest it unknowingly.

Don’t pour coolant on the ground either, as it can contaminate groundwater. If you spill any, you’ll need to clean it up immediately.

How To Clean A Coolant Spill

Use gloves and wear a mask to avoid inhaling it. Use an absorbent substance, like sand, kitty litter, or baking soda to cover the spill.

Use paper towels to cover the absorbent substance, then leave it alone for up to three hours.

Use new, dry paper towels to clean everything, then throw everything in a trash bag. Seal the trash bag tight, then clean your hands thoroughly.

Use soap and water to clean the area again, then use water to wash any leftover residue away. Leave the wet area to air dry, but if you wish, you can use paper towels or newspaper sheets to speed things along.

Clean your hands again after cleaning the area, and don’t touch anything until you’ve done so.


You should never use water as coolant as it is easily affected by extreme temperatures. If it boils or freezes, engine damage may occur, which can be expensive to fix later.

Always make sure that your coolant is the right one for your vehicle, and keep checking the coolant level and fan to avoid problems.

Remember, coolant is toxic, so keep it out of reach from children and pets. Take care when handling it, and clean up any coolant spills as soon as possible.

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