How Do Hot Tub Jets Work?

How Do Hot Tub Jets Work?

Often when we daydream about taking a relaxing soak in a hot tub, we are thinking about the relaxing hydrotherapy benefits and not about how the jets in the hot tub work. But, in case you are curious, here is a rundown of how spa jets work as well as some common troubleshooting tips.

Hot Tub Jets 101

The jets in a hot tub have three main connections, which are air in, water in and an air mixture outlet. The pressure from the hot tub pump pushes water into and through the jet until it flows out the front. The air also gets mixed into the pressurized water stream, by use of what is called a venturi, which is a small hole inside of the jet where the all the water gets directed through. This is usually referred to as the ‘venturi effect.’

Essentially what happens is that if the size of a pipe becomes reduced by the water moving through it, the speed of the water increases but the pressure inside the pipe decreases. This reduces the incoming water feed and forces it through a small hole. Since the air outside of the jet is a higher pressure than the water coming from the tip of the pipe, air gets forced into the water stream and mixes into the water. This is what causes the pressurized air/water mixture which flows from the front of the spa jets.

Hot Tub Jets Not Working

Now that you know how a hot tub jet works, let’s take a look at some of the common reason why hot tub jets may not be working at times. These can include:

Drain Cover:

Drain covers are located near the footwell area of a hot tub and have very strong suction. If they become blocked by something like a napkin, cup or plastic, it will block the flow of water. If you are having problems with your water jets, one of the first items to check would be the drain cover.


Your water flow can be dramatically reduced by a dirty spa filter. If your water flow rate is low, the water heater will generally not work. If your heater is running, chances are the filter is functioning properly. If your filter is dirty, small particles of dirt and debris will pass through, disrupting the water flow as well as contaminating the water.

Air Leak:

If an o-ring is out of position on the pump, or a loose or cracked valve, the pump will end up sucking in air when the pump is on and leaking air when the pump is off. To inspect, open your hot tub cabinet, shut off the pump and watch/feel for any dripping or spray that is on the pipe running from the pump.

Clogged Jet:

It is not very common, but hot tub jets can become clogged. When this does occur, it is usually a result of a broken part that has become trapped inside and is blocking part of the water flow. With most hot tub models, the individual jets can be removed and inspected.

Low Water Level:

If your spa skimmer is sucking in air, this will seriously impact your hot tub water flow and could shut down the heater. Make sure that you frequently monitor and add replacement water when needed to replace any water that has been splashed out of the tub or has evaporated. Using a tight, locking cover can help prevent water evaporation.

Now that you know how hot tub jets work and what some common issues are with water flow, download a hot tub buyer’s guide to learn more about the other features hot tubs have to offer.