Water Cooling Guide | Everything You Need To Know


A custom water cooling loop can be very daunting at first. The many parts, price and complexity can shy off a lot of people.

This guide is meant to help you understand water cooling much better. And who knows, maybe your next build will include one.

How It Works

In a custom water cooling loop, there are 5 main components. The tubing, reservoir, pump, radiator and CPU/GPU block.

The first part we need in a water cooling loop is some way to transport the liquid. The standard is using either a soft or hard tube.

Soft tubing are made out of silicone, rubber or PVC. Hard tubing is made out of either acrylic or PETG.

The tubing fits onto the other components using water tight fittings.

Custom Wtaer Cooling Parts

Most beginners loops have a pump and reservoir combo, saving space and money.

The reservoirs job is to store the cooling fluid when not in use. The pump is used to pump the fluid from the reservoir to the block or radiator depending on your setup.

The component that cools your fluid is called the radiator. Like with AIO water coolers this can range in size and is fitted with fans.

These then pull or push air through the radiator, cooling the liquid.

The last main part is the CPU/GPU block. This part is mounted on top of the component you want to cool.

Then the cooled liquid passes through, which then cools the component.

Pre-Made Kits

Pre-made kits are a good option for beginners. No need to look for all the parts and make sure you have got everything.

These kits are available in different variations. From radiator size to how many reservoirs, many of these kits are customizable to your liking.

Here are a few examples of pre-made kits:

Soft Tubing 360 Radiator (Advanced) – EKWB X360

Hard Tubing 360 Radiator (Medium) – Thermaltake Pacific M360

Soft Tubing 360 Radiator (Medium) – EKWB P360

Soft Tubing 120 Radiator (Simple) – EKWB S120


Like we already mentioned tubing is available in a soft and hard variant. Soft tubing is suggested for beginners but doesn’t look as clean.

Soft tubing doesn’t need any type of tools. You just need to cut it to size and install them to the components with fittings.

Hard tubing, on the other hand, takes a lot more planning and tools but is far more rewarding in the end.

The tools needed are available in bundles so you don’t need to buy them separately. The Thermaltake water cooling bundle includes everything you need.

The process of bending the tubes and cutting them to be fitted is too complicated to explain in this guide. Luckily there are enough tutorials on youtube.

There is no performance difference between the 2 so it’s just an aesthetic difference.

Tubes are available in different sizes. The most common are 12mm/10mm and 16mm/12mm. This is the outer and inner diameter of the tubing.


Fittings are available in all different colors giving PC builders another part which they can customize.

The main type of fitting is the compression fitting. This is a 2 part fitting, with one part screwing onto the component. The other part is the locking ring, which seals the tube against the other part.

Soft tube and hard tube fittings work in exactly the same way. Just that hard tubes only measure the outer diameter and soft tubes both the inner and outer diameter.


We like the soft tube fittings as well as the hard tube fittings from EKWB.

There are also special connectors which can have multiple uses. Most of these do need another compression fitting since they act as a “component” to connect the tubing.

Angled fittings are, like the name suggests, fittings that point in a specific direction. This can be useful when you need a tube to bend immediately after exiting a component.

These are available in 90-degree fittings and 45-degree fittings.

Keep in mind that these fittings do add up in price. So you might end up spending a lot of money on fittings when this is not needed. Just a little heads up.

Reservoir & Pump Combo

We are only going to cover the reservoir and pump combo since this is by far the main stream option. People who want a separate reservoir and pump probably already know what they are doing.

Reservoir & pump combos are basically a cup that stores your liquid. The pump sits under the reservoir, where you’ll also find the in and out ports for the liquid.

Reservoirs pretty much only vary in size, the rest is pretty much the same across different reservoirs.

Reservoir & Pump Combo

The pump on the other hand has different strengths. This determines how fast the liquid runs through your system.

The 2 main types of pumps are DDC and D5. Make sure your combo has a D5 pump like this one. D5 pumps have better flow rates and are quieter.

Starting at the top of the reservoir you will find a fill port. This is only used for filling your reservoir for the first time or after cleaning.

At the bottom, where the pump is, you will find 2 ports. One marked “in” and the other “out”. The in port is where liquid will enter the reservoir and the out port is where it will exit.

The best place to install your reservoir & pump combo is at the lowest point in the loop. This will help you when you want to drain your system which we will also cover in this guide.


The radiator in a custom loop isn’t any different than in an AIO. Warm liquid run through it which then gets cooled by the fans pushing/pulling in cool air.

Depending on your case configuration and what component is more important to you the radiator can be used as an exhaust or intake.


Radiators have 4 sizes: single, dual, triple and quad. These sizes are connected to the amount of fans you can mount, with 1, 2, 3 or 4 fans accordingly.

I suggest you go for the biggest radiator possible since this has more fans, making your system run quieter.

Another factor is thickness. This is not as important though, because it doesn’t affect performance by much. Just pick a thickness that fits in your case.

Radiators also have 2 ports marked with “in” and “out”. With the liquid flowing through each of the ports accordingly.


Like we already mentioned, the block sits on top of the CPU/GPU and has cooled liquid flow through it.

water blocks are available in different variations. See through is the one we like most since you can see the liquid running through the block.

CPU blocks are pretty easy to install. Just apply thermal paste and then screw in your water block like any other CPU cooler.

The GPU blocks take some more work than the CPU blocks. You need to remove the existing cooler from the GPU to then install the GPU block.

Don’t worry though, youtube has a lot of tutorials on GPU water block mounting.

Like with the reservoir & pump combo and the radiator, the water blocks also have an “in” and “out” port. By now you can probably guess what each of these does.


It seems that everything has RGB these days. RAM, Cases and even cup holders.

Well, we actually like water cooling components to have RGB. It can help customize your build even more.

Reservoir & pump combos, water blocks, fans and even fittings are available in RGB. Here are our recommendations.

RGB Water Cooling

EKWB 140 Revo D5 RGB

EKWB 1080 Ti RGB GPU Waterblock

Thermaltake Pacific RGB CPU Waterblock

Thermaltake Pacific RGB Fittings

Installing The Loop

Since you know what all the parts do, now its time to assemble everything. Each of the components come with a good manual to show you where and how to install them to your case.

Like we already mentioned, make sure the reservoir and pump combo is at the lowest point of the loop.

There are 2 ways you can let your liquid run.

From your reservoir/pump to your radiator and then to your CPU/GPU.

Water Cooling Loop 1

The other method is from your reservoir/pump to your CPU/GPU and then to your radiator.

Water Cooling Loop 2

There is no real difference between the 2 so it’s up to you. Depending on how you case is configured one or the other might be better for running your tubing.

After you have installed all the components and connected them with tubing it’s time to fill your loop.

You do this by removing the 24-pin connector and connecting it to a dummy connector. You need this because you don’t want your PC to turn on and off the whole time.

This happens because you need to turn your PSU on and off to pump the liquid through your system. Fill the reservoir to the top, then turn on the PSU until your reservoir i almost empty.

Repeat this step until your whole system is full.

Then put paper towels under each of the fittings and water cooling components and let the loop run for 24 hours if possible. You keep the 24-pin connector connected to the dummy connector while you do this.

The paper towels protect your hardware from any possible leaks. After the 24 hours have past, and you have no leaks, you can connect your 24-pin back to your motherboard.

That’s it, you have successfully built a custom water cooling loop.


Sadly your not done forever. You need to drain/flush your system every 6-12 months depending on which coolant you are using.

There are a lot of video guides out there that show you how to do this.


This is where mounting your reservoir & pump combo at the lowest point comes in. By installing a Y-splitter to your “out” port on your reservoir, you can connect one part to your tubing and the other to a valve.

When wanting to drain your system just connect some soft tubing to your valve, put some sort of container underneath, and open the valve.

Then gravity does it’s job by pushing the liquid to the lowest point.


We hope we have helped you in understanding a custom water cooling much better. If you are going to water cool your next build, show it off at our setup showcase.

To finish off, here is a complete list of parts for a black and white build.

Black & White Water Cooling

Tubing – Thermaltake Pacific PETG Hard Tubing 500mm

Fittings – EKWB Compression Fittings 4 Pack

Reservoir & Pump – EKWB 140 Revo D5

CPU Block – EKWB Velocity RGB Intel

GPU Block – EKWB Vector RGB 2080

Radiator – EKWB SE360

Fans – Thermaltake Riing 120mm 3 pack

Coolant – Thermaltake C1000 White

Bending Kit – Thermaltake Pacific Bending Kit

Dummy Connector – 24-pin Bridge Tool

Valve – EKWB Ball Valve

Splitter – EKWB Y-Splitter

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