How to fit a fill port to a PC water-cooling system

Make refilling your PC water-cooling loop easier and less hazardous, thanks to the magic of a fill port positioned in just the right place.

Finished PC fill port

In this guide, we’ll show you how to fit a fill port to your PC water-cooling system. While it’s usually easy enough to fill a reservoir these days, doing this in close proximity to your hardware, or with your PC powered on, can be hazardous, as well as inconvenient.

Even after you’ve filled the reservoir and primed your loop, air bubbles can take hours or even days to work their way to the reservoir where they’re trapped, eventually resulting in the coolant level dropping.

A far easier way to fill or top up a reservoir in a water-cooling system is to use a fill port. Any spills will then happen away from your components, and you won’t even need to open your case’s side panel. Installing one is a simple job, plus the port itself will only cost you a few bucks.

At Custom PC, we’ve been modding PC cases and components since 2003, giving us loads of experience in the art of customizing your system to make it your own. We know exactly what tools you need and which methods work best.

1. Check for existing fill port hole

Install fill port

Some cases, especially high-end models from the likes of Phanteks and Fractal Design, already include the hole necessary to fit a fill port, usually in the top fan mount panel. It’s worth checking your case’s manual or product page first to see if it has one.

2. Identify fill port location

Install fill port

If you need to make your own fill port hole, it should be positioned above your reservoir, ideally in the roof of your case. You could add it next to the front panel ports, or even underneath a mesh panel, but you’ll need to check there’s clearance for it.

3. Mask up fill port area

Install fill port

You’ll be using a drill to cut the hole, and drill bits can easily slip and scratch your case’s paint. For this reason it’s essential to cover the area in masking tape, which will prevent damage to your case if this happens.

4. Mark fill port location

Install fill port

The fill port will have a specific size of shaft, and you need to use a step drill of this size, or a millimeter wider, but no more or you risk the port cover not hiding the hole. Mark the center position of the hole where you need it.

5. Use step drill

Step drill

A step drill can gradually open a hole with its graduated cutting sections, starting with a small one as an anchor point. A step drill will also enable you to cut into mesh areas, as in our example. A hole saw shouldn’t be used here, as it will tend to tear up the slim mesh sections.

6. Drill the hole

Drill hole into PC case

Remove all the hardware from your case, if you haven’t done so already. Then, when you’re ready to start drilling, use the weight of the drill to cut into the case using your step drill. Do this at a slow speed.

7. File the edges

File edges of PC case

Once the hole for your fill port has been created with the step drill, use a rounded metal file to smooth down the hole, as it will very probably be sharp and have a serrated edge.

8. Test-fit fill port

Test-fit PC fill port

Next, place the fill port into the hole. It should slot freely into place. Don’t force it or screw it into the hole, as the metal case can damage the plastic threads on the fill port. If this happens, file away more of the edge or open the hole another millimeter.

9. Connect fittings and tubing

Finished PC fill port

The fill port secures using a nut from underneath, leaving just a couple of millimeters on top. Both ends have a G/14″ threaded hole, with a port plug going in the top and your tube fitting in the base. This needs to connect to a port on the main reservoir chamber, ideally its main fill port.

Once you’ve fitted your fill port, you’ll wonder how you ever lived without it – this simple little port makes refilling and topping up your loop so much easier! For further water-cooling ideas, check out our full guide that shows you how to leak-test a water-cooling loop.

If you’re new to the world of water-cooling, then make sure you also read our full guide on how to water-cool your PC. If you’re planning a new build, then you’ll also want to read our full guide on how to build a gaming PC, which covers every step of the process.