How To Fill a Hot Tub – The CORRECT Way

fill a hot tub

Avoid Airlocks and Get Your Hot Tub Up and Running Quickly

Filling your hot tub with water may seem like a simple task, but if you do it wrong, you could end up with frustrating airlocks that prevent your jets from working properly. In this blog post, we’ll share the correct way to fill your hot tub, whether it’s a plastic shell tub or a DIY hot tub you’ve built yourself.

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Fill from the Highest Point

The key to avoiding airlocks is to fill your hot tub from the highest possible point. This forces air out of the pipes as the water fills them. For plastic shell tubs, this means filling through the filter. For DIY hot tubs, the highest point may be the tub itself, but if your control panel is lower than the tub, you’ll need to take extra steps to prevent air from getting trapped.

Purge Air with the Jets

Once the water level is above the inward suction drains, turn on the jets for 10-15 seconds. This will help purge any air that’s gotten into the system. Just be sure not to run the pumps dry, as this can damage them.

Run the System While Filling (Optional)

If you’re still having trouble with airlocks, you can try running the system while you’re filling the tub. This will help to push any trapped air out of the pipes. However, only do this if the water level is above the inward suction drains, and don’t run the pumps for more than short bursts at a time.

Tips for Stubborn Airlocks

If you have a really stubborn airlock, you can try lowering the water level below the jets and hot water returns, then running the system while refilling the tub. This should help to clear any remaining air.

Additional Resources

The video mentioned that the Buildahottub channel has other videos and blog posts on resolving airlocks. You can check out these resources for more detailed troubleshooting tips.


By following these tips, you can avoid airlocks and fill your hot tub with water quickly and easily. So grab your hose, turn on your favorite tunes, and get ready to enjoy a relaxing soak!

I hope this blog post is helpful. Please let me know if you have any questions.

Can I Help You?

If I can help you in any way I would love to hear from you. You can get in touch using the form below.

Thanks - Andi


Hi, Andi here. I own and also write all of the articles and info pages on the site. Some years back now, I built my own hot tub but struggled to find the information I needed. So, once my tub was complete, I started this website to help others in their own pursuit of hot tub and plunge pools DIY building information.

Today, I've helped over 1000 DIY customers just like you all over the world build hot tubs and pools. Have a good look around the site, there are lots of resources here. Please do get in touch if I can help you. - Cheers, Andi

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