What Liquid To Use In Water Cooling A PC? (Explained)

Water cooling is a great way to keep your computer cool and quiet.

It’s a necessity for hardcore gamers and overclockers.

However, running liquid through any computer system can be messy and dangerous.

That’s why you need to pick the right liquid to cool your parts in addition to correct installation.

Let’s take a look at what liquid to use when water cooling your PC and the properties of an ideal coolant.

What Liquid To Use In Water Cooling A PC?

Distilled water should be your first choice for liquid cooling a PC.

Water is one of the materials with the highest ability to absorb and transfer heat.

Moreover, distilled water is electrically non-conductive.

If you’re a first-time builder, it can reduce the chance of damage due to leaks and improperly sealed fittings.

It’s also cheap and readily available at any supermarket.

However, you can’t simply pour distilled into your loop.

You must add an antibacterial agent to prevent algae and other organisms from growing in your loop.

Alternatively, you can add a piece of silver to your coolant instead of biocide because silver has natural antibacterial properties.

A corrosion inhibitor is also necessary to protect the aluminum and copper in your radiator and water block.

Finally, some water cooling experts like to add a couple of drops of dishwashing soap to their coolants.

They claim it gets rid of bubbles faster and reduces pump noise.

However, many other experts disagree.

Beginners should avoid this practice.

If you want to add some color to your coolant, buy a dye designed for water cooling.

Avoid food coloring as it causes bacterial growth and eventually blocks your loop.

Also, purchase your dye from a reputable brand to ensure perfect results.

You can also find various premixed solutions on the market that eliminate the hassle of mixing water and different chemicals.

Depending on their chemical composition, these solutions come in different colors and work between three months to three years before you have to replace them.

1. Distilled Water

Pure distilled water is the most common non-conductive coolant.

Non-conductive coolants aren’t entirely safe if they leak.

These coolants are initially non-conductive because their ions and minerals have been removed completely.

However, as they pass through your loop numerous times, they collect ions from the radiator and other loop components.

They gradually regain their conductivity properties.

Therefore, a more effective solution is to use deionized water with some biocide to inhibit bacterial growth.

You should also periodically inspect your system for leaks and immediately take action if you discover any.

Warning: If you notice any leaks in your loop, dry the liquid with a paper towel and give your computer at least 24 hours to dry.

Starting the computer with water on the components can cause short circuits and kill your motherboard.

2. Deionized Water

Deionized water is similar to distilled water but has undergone complex chemical processes and filters to remove over 99 percent of its dissolved minerals.

In contrast, distilled water is only vaporized water that has been converted back into liquid.

It may contain a large portion of its original mineral content.

Deionized water is much more expensive than distilled water due to its complex production.

It’s also not as readily available.

Moreover, it has higher corrosive properties because removing the ions requires applying extensive energy to the water.

This extra energy increases the liquid’s tendency to react with metal ions.

Properties Of The Ideal Liquid Coolant

The perfect PC coolant must absorb ample heat and transfer it to the radiator.

It must also flow through the system easily and conduct as little electricity as possible for safety reasons.

Let’s explore these characteristics more closely.

By the end of this section, you’ll understand why distilled water is the best choice for cooling your PC.

1. Thermal Conductivity

Thermal conductivity refers to a material’s ability to transfer heat.

Common metals, such as copper, aluminum, and nickel, are famous for their high thermal conductivity.

Although water isn’t as conductive as these metals, it outperforms many other fluids.

Specifically, it’s thirty times more conductive than air and twice as much as methanol.

2. Heat Capacity

This parameter is the flip side of conductivity.

It refers to how much heat a material can absorb.

More precisely, it determines how much heat is required to increase the material’s temperature by one degree (Celsius).

Water’s heat capacity is higher than any other liquid and metal.

A custom loop containing one liter of distilled water can absorb over 4,000 joules of energy before its temperature goes up by one degree (Celsius).

That’s over ten times the capacity of copper and forty times that of aluminum.

Your CPU should run under full load for around a minute to generate that much energy.

3. Viscosity

Viscous fluids don’t flow very smoothly.

Think of honey and/or engine oil.

Water has ideal viscosity.

Therefore, it’s easier to pump and dissipates heat more efficiently.

You can add surfactants to the water to reduce its surface tension and boost its viscosity.

These are readily available in most detergents, like soap and dishwashing liquid—one or two drops are sufficient.

4. Electrical Conductivity

Unlike what many people think, pure water doesn’t allow electricity to pass through.

Instead, the dissolved minerals in the water make it conductive.

Therefore, you can determine your fluid’s quality by measuring its conductivity using a multimeter.

High-quality distilled water won’t cause short circuits if it spills on your hardware.

Common Coolant Additives

1. Ethylene Glycol

Ethylene glycol is a common component of antifreeze products.

The organic compound is also a very common coolant in closed-loop systems.

It acts as a biocide and corrosion inhibitor.

However, it’s denser than water and has a lower heat capacity.

Therefore, a pure ethylene glycol coolant won’t transfer heat effectively.

The material is also highly toxic.

Therefore, it’s only used in closed-loop systems where people are unlikely to come into contact with it.

2. Propylene Glycol

This synthetic compound is the non-toxic counterpart to ethylene glycol.

It has the same antifreeze, biocidal, and anti-corrosion properties and is a common food additive.

Many manufacturers use it to create eco-friendly automotive antifreeze.

You can add it to your PC coolant in small concentrations (no more than 15 percent of the solution).

However, a super coolant designed for water cooling can be significantly more effective.

3. Dyes And Colors

Using non-clear fluid is usually not a good idea, despite the aesthetic appeal.

Adding dyes to your coolant can cause a sticky mess, depending on the mixture concentration and type of dye.

Gel-like dyes that create an opaque effect are more likely to cause this problem.

The dye particles tend to separate from the fluid and accumulate in a low or narrow part of your loop.

Moreover, mixing the dyes manually to create a custom color may cause a pH imbalance that corrodes your radiator or promotes bacterial growth.

This situation leads to a gradual build of an unpleasant, slime-like substance, which may eventually block water flow and bring your cooling system to a halt.

The most hassle-free option is to buy a premixed cooling fluid of your preferred color.

However, if you insist on mixing the solution, we recommend darker colors like blue and green.

Brighter colors, especially red and orange, are notorious for wreaking havoc on your loop.

4. Other Materials

It’s amazing to see the claims some manufacturers make to attract customers.

You may see ads for coolants with special materials that boost thermal conductivity or increase heat capacity.

However, most of these claims are bogus.

In general, you don’t need anything more than a distilled water solution with a growth inhibitor and anti-corrosion agent.

Always be skeptical of bold claims.

For example, watch how this YouTuber found a supposed graphene coolant has no thermal advantage over regular coolants:

5. Premixed Solutions

A premixed coolant takes all the hassle out of filling your loop.

These solutions come in concentrated and diluted forms.

If you buy a concentrate, you have to dilute it with water.

They’re always more expensive than distilled water but have a few advantages:

They contain the exact necessary amount of growth and corrosion inhibitors.
You get the color you see instead of messing up the coloring yourself.
Some solutions create cool visual effects as they travel through the loop.

Despite these advantages, colored coolants can cause gunk and sediment in your system.

Therefore, always buy products from reputable brands, such as EK and Corsair.

Warning: Leaving an opaque coolant in a loop without turning on the computer has serious consequences.

You’ll experience buildup, gunk, discoloration, and corrosion.

Let your computer run at least weekly so the fluid can mix.

Can You Use Antifreeze To Cool Your PC?

You can use antifreeze to cool your PC, but it has no thermal advantage over distilled water.

For one thing, unless you live in a cold country and leave your computer outside for a long time, your coolant will never experience sub-zero temperatures.

Secondly, it can ruin your setup under certain circumstances.

As explained earlier, ethylene glycol is a common component of antifreeze products.

Never pour antifreeze in tubes made of Polyethylene terephthalate glycol (PETG).

The ethylene glycol in antifreeze reacts with the glycol in the tubes and causes leaks.

Although the chemical reaction isn’t immediate, your system will break within a few days or up to a month.

How Often Should You Change Your Liquid Coolant?

To answer this question, we’ll assume you have a custom loop as closed-loop coolers or AIOs don’t need liquid replacements.

They usually work for about three years or until one of the components dies.

If you want to keep everything clean, empty the loop every year.

Also, clean your reservoir and radiator to remove potential gunk and growth.

However, distilled water and other clear coolants don’t require much maintenance.

In reality, you don’t have to replace them as long as the system works without trouble, especially if you have clear tubes.

On the other hand, colored solutions need frequent flushing and refilling.

For example, if you have an opaque coolant, you should change it every three to six months.

Other colored mixtures shouldn’t be in your system for longer than a year.

Otherwise, the coolant may clog up your loop and force you to take the entire loop apart.

If you notice discoloration or layering in your coolant, flush it out and refill the loop as soon as possible.

Otherwise, you risk damage to your components.

You may even have to uninstall the loop and thoroughly clean all the components.

Oxidation, powdery residue, or corrosion in your radiator are other signs to watch out for.

Sediment buildup is especially common on the fittings and o-rings.

Before installing the radiator, fill two-thirds of your radiator with hot distilled water and shake it.

Then empty the water into a sink or bowl.

Repeat the process a few times until the outgoing water is completely clear.

Doing this simple task saves you immense trouble down the time because the debris and metal particles in the radiator can easily end up in your loop and cause clogs or tear your tubes.

Warning: Some coolants are illegal to flush down the drain because they erode the pipes or contaminate the environment.

Read the instruction manual and research how to dispose of your coolant before flushing it.

Warning: If your coolant contains toxic compounds such as ethylene glycol, wear protective gear when cleaning the fittings.

Frequently Asked Questions

1. Are Non-Conductive Coolants Safe?

Non-conductive fluids are effective if you’re a first-time builder.

That’s because you’re more likely to make a mistake that leads to a leak.

With a non-conductive coolant, you won’t damage your computer when you turn it on for the first time after finishing the loop.

However, remember that these coolants eventually become conductive as they collect contaminants and metal ions from your radiator, cooling blocks, pump, and tubes.