Why You Should NEVER Turn On a Hot Tub Without Water

Jennifer Rhodes

By Jennifer Rhodes · Updated

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A common question new spa owners have when setting up a hot tub for the first time is when to turn it on: should you add the water first?

You should never turn on a hot tub without water. Only turn on a spa once it's full, and all the jets are fully submerged. If you don't do this, you risk damaging the pump, which can be costly to replace.

Many people don't realize that it can actually be quite dangerous to turn on a hot tub without water too. Doing so can not only damage the pump and overheat the motor, but potentially cause an electrical fire.

In this blog post, we'll explain why you should never turn on a hot tub without water—and offer some tips for adding water to your hot tub safely.

Why you should never turn on a hot tub without water

When you turn on a hot tub without water, the main risk you run is damaging the pump. The pump is responsible for circulating the water in the hot tub and keeping it at the right temperature. Pumps are not meant to be run without water, and doing so can cause them to overheat.

Why? When there is no water to circulate, the pump will continue to heat the air around it until the temperature reaches a dangerous level. This can damage the pump, or even cause it to catch fire in extreme cases. If the pump is damaged, it can be very expensive to replace.

Even if the pump doesn't break completely, continual circulating of air can lead to premature wear and tear, which will shorten its lifespan.

And not only that; damage to a pump that is obviously caused by you running the spa without water will likely void any warranty that you have on it.

What other ways can you damage a spa pump?

Running a spa empty is not the only time a pump is at risk of overheating. It can also happen due to something called an airlock.

What is an airlock?

An airlock is when air gets trapped in the hot tub lines and pump, causing it to overheat. This usually happens when the water level in the hot tub is too low, or after a drain and refill when the water doesn't quite fill everything like it should.

When you turn on the spa, it will draw in this air and form an air pocket inside the equipment. If this pocket of air isn't released, it can cause the pump to overheat and potentially break.

How to spot if you have an airlock

The classic sign of an airlock is when you turn on the jets and nothing comes out. You can hear the pump running, but there's simply no sign of any water being circulated.

How to fix an airlock

Luckily, airlocks are a simple problem to fix. This video explains how to do it:

Tips for adding water to your hot tub safely

Now that we've explained why you should never turn on a hot tub without water, let's talk about how to add water to your hot tub safely. The first thing you need to do is, as we all know by now, make sure that the power is turned off. Now you can remove the cover and begin filling the hot tub with a hose.

It's best to insert your hose into the filter area so it can be filtered as it goes in.

Alternatively, you can get hose attachments that will filter the water while you are filling your tub. This can reduce the mineral content, which is helpful especially if you live in an area with hard water:

Guardian Max Clear PRO Hot Tub Garden Hose Carbon Pre Filter
Guardian Max Clear PRO Hot Tub Garden Hose Carbon Pre Filter
View on Amazon

Once you've added enough water to reach your desired level (remember, the uppermost jets need to be fully covered), you can turn on the power and begin heating the water.


I hope this blog post has convinced you of why you should never turn on a hot tub without water. Not only does it risk damaging the pump, but it can also overheat and become a fire hazard.

So, what should you do if your hot tub is empty? The best course of action is to simply fill it up with water before turning it on. This may take some time, but it's well worth it to avoid any potential damage to your hot tub. Once the hot tub is full, you can then enjoy it without worry!

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