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How Does a Hot Tub Work?

Want to know how your hot tub works? In this article, we explore each vital component within the hot tub system to understand how everything functions together.

The basic functionality of a hot tub is to heat, circulate and pump water through massage jets to give users a relaxing and enjoyable experience.
outdoor hot tub
Water Supply

The first step in getting your new hot tub running is to fill it with clean water. You'll need to fill your hot tub via a garden hose or tap extension. Once your hot tub is filled to the required depth, the water should then be sanitised before first use and periodically changed throughout the year.

Some new hot tub owners are surprised to learn this fact as they believe the water supply is plumbed into the hot tub via the main water supply. However, filling and emptying the hot tub with a standard hose pipe is a much easier process and helps to save water.
garden tap
Water Circulation

Your hot tub works using something called a 'closed loop' system. This means that unless fresh spa water is added, the same water will cycle through the spa repeatedly. It's crucial to keep the water flowing constantly because it avoids stagnation and allows the filter to continuously remove dirt, debris and bacteria, thus preventing it from circulating through the spa.

Hot Tub Power

Hot tubs can be powered in various ways including standard electrics, solar power, gas power and even wood fired. Most hard shell, home hot tubs however run using electrical power. There are two types of electrically powered hot tubs: plug and play hot tubs which are plugged into a standard power socket and mains powered hot tubs which are wired directly to into your domestic power supply. Because they are plugged into a wall socket, plug and play hot tubs tend to be smaller as they have a maximum of 13 amps.
hot tub control panel

Every hot tub must be heated in one way or another and for standard home hot tubs, this is by means of an electrically powered heater. Water is run through the hot tubs heating element via the circulation pump where it is heated to required temperature set by a controlled thermometer.
hot tub bubbles
Hot tub Operation

Hot tubs function using a closed loop system. Let's take a look at how this operates below..

All hot tub components work together to create your hot tub experience. The closed loop system which is circulated by the hot tub's pump runs water through the heater and filter to keep the water hot and clean.


The first point of action inside a hot tub is suction. Water is taken into the suction line via a drain which usually sits on the floor of the tub and a skimmer which sits just below the water line.

Once water is drawn in through the suction line, it makes its way towards the hot tubs circulation pump. Most hot tubs use two pumps: circulation pumps and jet pumps. Circulation pumps work to circulate the water throughout the spa whereas jet pumps are responsible for sending water to the spas massage jets.


The circulation pump pumps water through the heater and filter to clean out debris and heat the water.

Some hot tubs may be fitted with an ozonator. Ozonators are a secondary filtration and sanitisation system which use ozone gas to break down large contaminant particles as well as kill harmful microorganisms. If the hot tub is equipped with an ozonator, the water will pass through it once it has been heated and filtered. The next and final step of the hot tub water within the closed loop system is the return line. Here the water is pumped through a manifold diverted and sent to various points around the hot tub.