How To Top Up Your Open-Loop Coolant
Complexity: Intermediate | Time: 10 min | Tools: Distilled Water only, Paper towels or a clean cloth, A small squeeze bottle or a bottle with a narrow spout (recommended)
It's not uncommon for your coolant level to drop slightly over time as it evaporates. Dissipation of about 1-3cm is expected and does not impact the loop’s performance, but it is possible to perform small top-ups yourself using distilled water.
Here’s how to safely top up your water cooling system to keep it running smoothly!
Important: this guide does not apply to all-in-one CPU coolers.
Before You Start (Important)
We recommend using a squeeze bottle with a telescopic tube to perform this top up. Distilled water is widely available at stores like Amazon, Bunnings, Coles, or Woolworths. Do not use tap water, filtered water, or demineralised water.
Important: Using anything other than distilled water can disrupt the coolant balance. This can cause colour degradation, and may result in build-up of sediment or even algae growth inside the cooling loop. A full drain and refill service is needed in these cases.
• Shut down the PC normally.
• Switch the power off at the wall and unplug the power cable.
• Let the system cool down for 10–15 minutes, if it was recently running.
• Place the PC on a stable, flat surface (a desk or table). Avoid benches/edges where it could be knocked or tipped.
If you can see an active leak, pooling liquid, or coolant spraying/misting, do not top it up. Contact Aftershock PC Support first.
Safety Cautions
Keep Liquid Away from Electronics
Avoid getting coolant or water on any electrical components (graphics card, motherboard, power supply, cables). Liquid on electronics can:
• Cause short circuits
• Lead to corrosion over time
• Result in permanent damage if powered on while wet
If you spill any liquid inside the PC: do not power it on. Contact support for advice before attempting to start it again.
Protect the Area
Before removing the cap/plug:
• Stuff absorbent paper towel around the working area (below and around the fill port, between/on top of/inside any sensitive components), so any drips are caught before they can run onto components.
• Keep extra paper towel nearby for quick clean-up.
Helpful Notes
• A small coolant drop over time is normal. If you’re topping up very frequently, please let us know as there may be something else going on.
• If the coolant looks cloudy, has particles, or you’re unsure what liquid is in the system, contact support before adding anything.
• Do not attempt to perform a full replacement of the coolant yourself. If you would like to have the coolant fully changed, just contact our Support team and we can have your PC serviced.
Steps to Top Up the Coolant
Access the Fill Port
Most systems have the fill point in one of these places:
• Top of the reservoir, or
• A fill port on the distribution plate (often near the top)
It will usually look like a small cap/plug (sometimes coloured).
Prepare Spill Protection
• Place/pack paper towel around and below the fill point.
• Keep the squeeze bottle and extra paper towel within reach.
Remove the cap/plug
• Unscrew the cap slowly (counter-clockwise) and set it aside somewhere safe.
You may need a tool to unscrew it: any compatible tool that fits the stop fitting will work.
Filling the Reservoir
Cylinder Reservoir
• Using the squeeze bottle, slowly add small amounts of distilled water at a time.
• Pause briefly between pours to let the level settle.
• Fill until the level is near the top of the reservoir, or roughly up to the bottom of the fill opening (so it won’t overflow when you reinstall the plug).
Distribution Block
• Tilt the PC on its back (or angle it) so the air pocket is around the filling port.
• Using the squeeze bottle, slowly add small amounts of distilled water at a time.
• Pause briefly between pours to let the level settle.
• Fill until the level is roughly up to the bottom of the fill opening (so it won’t overflow when you reinstall the plug).
Reinstall the cap/plug (do not overtighten)
• Screw the cap back in until it is snug and sealed.
Be careful not to overtighten. Tightening too hard can damage threads or crack acrylic parts (especially relevant to PCs with distribution blocks).
Clean and Check
• Carefully remove the paper towel you packed around the area.
• Wipe away any drips.
• Look closely around the fill point for any signs of moisture.
• Make absolutely sure that no coolant has leaked onto any electrical components before you proceed. Even if you've already double-checked, now is the time to triple-check!
Turn On the PC
• Plug the system back in, switch power on at the wall, and start the PC.
• Watch the reservoir/fill area for the first minute to confirm everything stays dry.
What's Next?
If you’re unsure where the fill port is, if you have any other questions or concerns, or if you’d like us to handle it, we can assist with support guidance or organise a service. We’re here to help ensure your system operates at its best!
