top of page
  • Writer's pictureAqua Warehouse

What is a Hot Tub and How Does it Work - Ultimate Beginner's Guide

Updated: Jan 4, 2023

You’ve probably already got a basic idea of what hot tubs are otherwise, you wouldn’t be thinking about getting one. You know the water circulates, and it’s supposed to be very relaxing and luxurious, but what else do you know?

In this post, we’ll give you the complete picture, including the parts, the plumbing, how to take good care of your home spa, how much hot tubs cost, and their benefits.

By the time you reach the end of the post, you’ll have all the facts and be ready to make your purchase.

Before you know it, you’ll be lying back enjoying a bubbly and luxurious soak in your very own personal outdoor spa.

What is a Hot Tub?

What is a Hot Tub

The official definition of a hot tub, according to Merriam-Webster, is a large tub of hot water, especially one that’s equipped with a whirlpool device, in which bathers soak and socialise.

Hot Tub Origins

Let’s start this post by looking at where they came from. The earliest were called calderas. These were just a bathtub that used hot stones to heat the water.

One of the first examples of a hot tub was at Therma in Ikaria. It was a popular place for hydrotherapy as long ago as the 4th century BC.

In 737 AD Japan, hot springs and bathing facilities first opened near Izumo, Shimane. Fast forward to the 8th century in Japan, and the first ryokans were built. They offered visitors food, accommodation, and soaking tubs that they called ofuro.

Ancient Romans also enjoyed the whole bathing experience. There were baths in their homes, private baths, and public baths. When occupying foreign lands, even Roman legions would build their own baths where they found thermal and mineral springs.

After the Roman Empire fell in 476, bathing was abandoned thanks to Christianity. It wasn’t until the 13th century that baths gradually came back into re-use, particularly in southern Europe.

Hot tubs only began to appear in the US in the 1940s. They took their inspiration from the Japanese ofuro. Jacuzzi introduced the first hydrotherapy pumps.

Fibreglass shell models didn’t appear until around 1970, and these were soon superseded by shells made using cast acrylic.

Are Hot Tubs the Same as a Jacuzzi?

The word jacuzzi has become synonymous with the words hot tub, but it’s just a trademarked brand name.

Nevertheless, Jacuzzis has become a commonplace term people use when talking about hot tubs. There are, however, some crucial differences between hot tubs vs. jacuzzis.

  • Hot tubs: These are large tubs that contain hot water. You can use one for relaxing and entertaining.

  • Jacuzzi: This is a trademarked brand of hot tubs and various other products.

How Does a Hot Tub Work?

Hot tubs are self-contained tubs that provide users with somewhere to relax and destress. Essentially, they circulate water and include parts that help to keep the water clear and clean.

The operational parts of a hot tub endlessly cycle your water as long as your hot tub is running. This process prevents the water from stagnating, distributes chemicals, and lets the heater and filer do their job.

The plumbing of your tub provides a steady stream of water so that the jets can deliver the full hot tub experience.

Here’s how the operational side of your hot tub works:

  • Suction: Water is sucked out of the hot tub or spa and into the filtration system. The parts that perform this process are the pump, skimmers, and the suction line.

  • Filtration: The filtration system filters the water and heats the water sucked in. The essential components for this process are the pump, filter, heater, and sometimes, an ozonator.

  • Return: This is when the clean, heated water is pushed back out into your hot tub. Parts that perform this action are the pump, return lines, manifolds, PVC tubes, and jets.

To understand how a hot tub works, you need to understand the different parts and components.

What are the Different Parts and Components of a Hot Tub?

The main component parts of a hot tub are:

  • The Shell

  • Pumps

  • Spa Pack - Controller and Heater

  • Hot tub filter

  • Topside Control System

  • Oxonator

Now, let's go into some information about each one:

The Shell

The shell is what holds the water. You’ll find them in a wide range of shapes, sizes, and colours. Most have been moulded to include seats. The shell also has holes in it where jets can be installed. The jets help to circulate the water.

On the underside of the shell, it’s usual for there to be an insulating layer that helps to keep the heat in.


The pumps circulate the water in and out of your hot tub. They help to operate the jets and filter the water. In essence, they are the heart of your hot tub’s filtration system.

When the pumps are on low speed, they filter and help to heat the water. A spa pack controls them, and a thermostat regulates them.

When on high speed, the pumps operate the jets. The jets are controlled by the spa pack air button, which in turn allows for high-pressure steam.

The jets work by drawing air through a nozzle, which is a constricted section of the jets. This action creates a pressurised effect that is soothing and massaging for the person sitting in the spa.

Spa Pack - Controller and Heating Element

The spa pack contains a heater and controller. The controller controls all the functions of hot tubs, from turning the jets on to filtering and heating.

When water circulates through the heater, it heats up the spa.


Filters have a crucial role to play because they keep the water in hot tubs clear and clean. Replacing and cleaning the hot tub filter regularly is crucial.

Topside Control

You use the topside control to change the temperature of the water. As well as controlling the water temperature, the topside control also controls the lights, pumps, and blowers.


Spa owners are choosing to use these more and more to help them keep the water as clean as possible. They tend to be an optional add-on. If you install one, you have to locate it after the heater.

An ozonator generates ozone gas then injects it into your hot tub’s water. The ozone removes pollutants in the water, thereby reducing the level of sanitising chemicals needed.

There are two types of ozonator: corona discharge (CD) or ultraviolet light (UV). CD ozonators have a longer lifespan, tend to be more efficient, and are smaller. All of these features make the CD Ozonator the most widely used.

Now you know your hot tub's different parts and components, let’s move on to the different types.

What are the Different Hot Tub Types?

As we’ve already mentioned, hot tubs come in many different shapes, sizes, and styles. Some of the most popular ones include:

  • Portable

  • Wet-jetted

  • Air-jetted

  • Wood-fired

  • Inflatable

Portable Hot Tub

Portable hot tubs are also called prefabricated hot tubs. The name portable is kind of a misnomer as there would be a lot of heavy lifting required if you ever wanted to move your portable hot tub.

You can purchase portable hot tubs in various sizes and different materials. They tend to be slightly more affordable than other types and more energy efficient. You have the option of installing one inside or outside your home, sinking it into the ground, or installing it on the floor. You could also build decking around it to create a more custom look.

Wet-Jetted vs. Air-Jetted Hot Tubs

The main difference between these two types of hot tubs is the mechanics.

  • Air-jetted hot tubs: The air jets in this type of hot tub collect the surrounding air, heat it, and then blow it out into the hot tub. This means you get to enjoy a constant stream of rolling water.

  • Water-jetted hot tubs: Water jets, on the other hand, gather the tub water and shoot it out from the jets at high pressure.

Wood-fired Hot Tub

A wood-fired hot tub works using the principle of gravity. Pipes run around the inside of a wood burner. As the water in the pipes is heated by the fire, water flows upwards out of the pipes at the top into the tub. Cooler water flows into the pipes from the bottom of the tub into the furnace.

Inflatable Hot Tub

Inflatable hot tubs are a good entry point for anyone looking to get a taste of the hot tub lifestyle. They can be great fun, but the downside is that there are very few bells and whistles. There will be jets, but they produce little more than bubbles, and then only when the heat is off.

You can use inflatable hot tubs outside, but it’s not recommended below a certain temperature.

What are the Main Hot Tub Sizes and Dimensions?

Hot tubs tend to be categorised into three sizes: small, medium, and large.







​5’4” – 7”

5’4” – 6’8”

​2’4” – 2’9”

​2-4 people


6’6” – 7’9”

6’4” – 7’9”

2’7” – 3’2”

5-6 people


7’ – 9’

7’ – 9’2”

3’ – 3’3”

Now you’ve got a rough idea of the possible hot tub sizes and dimensions, you’ll be able to check what size fits in your garden before you head to a showroom or make a purchase online.

Are Hot Tubs Healthy?

As long as you maintain your hot tub, keep it clean and achieve the right chemical balance, you can enjoy many benefits when you soak in your hot tub.

1. Stress Relief

This is the most obvious benefit of relaxing in your hot tub. Your home spa has the potential to ease the tensions of the day away. The warm water and the massaging action can be very soothing and may help relieve emotional, mental, and physical stress.

If you want to ramp up the experience, you can also add soft music, aromatherapy, and low lighting.

2. Muscle Relaxation

The warmth of the water and massaging action can also be very effective at relaxing and soothing tense and tight muscles. In turn, this helps to ease any aches and pains.

If you have a soak in your hot tub before exercise, it could also reduce the risk of injury.

3. Improved Sleep

Research has shown that simple relaxation while soaking in a hot tub might be enough to help you drift off into a more peaceful sleep.

4. Pain Relief

It’s possible that relaxing in a hot tub may relieve some types of pain because it relaxes tense muscles, tendons, and joints.

If you suffer from arthritis, the heat and massaging action may help ease the stiffness and inflammation that can cause pain.

In addition, as the water supports your body it’s taking weight off your joints. This helps improve flexibility and range of motion.

5. Better Cardiovascular Health

When you relax in a hot tub, it can raise your heart rate and lower your blood pressure.

As you can see, there are several benefits for your health when you own and enjoy a hot tub. However, you can only enjoy these benefits if you maintain your hot tub and treat the water.

Hot Tub Maintenance and Water Treatment

Maintaining your hot tub is vital. Equally important is treating the water. Both will ensure your hot tub is clean and free from bacteria, thereby providing a safe and pleasant hot tub experience.

Some of the basic hot tub maintenance elements you must include are: sanitising, pH adjustments, shock treatments, plumbing and repairs.

Water Sanitisation

You must use a sanitiser to control and prevent bacteria growth. Maintaining the appropriate level of sanitiser in the water will ensure any bacteria enjoying your warm spa water is killed.

The two main sanitisers are:

  • Chlorine: Chlorine is the most popular choice because it’s cost-effective and acts quickly. You can purchase chlorine as granules or tablets.

  • Bromine: Bromine is a very effective alternative, but it tends to be more expensive than chlorine and takes longer to work.

There is one other option, and that’s a salt system. This system uses saltwater to generate chlorine and active oxygen. This kills the bacteria very effectively. In addition, it’s more convenient and leaves the water feeling more natural.

Hot Tub Water Balancing

There is a very fine balancing act you need to take charge of when you own a hot tub. The pH level of your hot tub water has to be maintained at the optimum level if you want to avoid problems such as build-up of scale, cloudy water, skin and eye irritation. In addition, your sanitiser will not work as efficiently.

The ideal pH level is between 7.2 and 7.8. You should test the pH level of your spa water regularly using a pH test kit or testing strips.

Shock Treatments

As well as using a sanitiser, it’s also recommended that you use a shock treatment once a week. The shock treatment does several things, for example:

  • Breaks down pollutants such as dead skin or perspiration

  • Kills bacteria

  • Removes organic compounds

Plumbing and Repairs

If you follow a regular maintenance schedule it will reduce the need for any repairs. However, even with strict maintenance, there will come a time when your hot tub needs to be serviced or repaired.

You should be able to deal with any minor issues, but more serious problems will need to be fixed by a professional hot tub repair company.

Hot Tub Cleaning

Cleaning hot tubs plays a critical role in their maintenance. A common problem is scum, for both indoor and outdoor tubs. You’ll also need to remove leaves, rubbish, or unwelcome visitors that might fall into the water if your spa is outdoors.

Cleaning hot tubs is a very quick and easy process. You use a sponge and white vinegar to clean the shell and jets as well as remove any scum line. For your hot tub’s cover, a mild bleach/water solution should clean it very well. Before you replace it, make sure the cover is completely dry as this will help to prevent mildew.

Cleaning, maintenance, and choosing the proper hot tub chemicals might seem like a lot of work to do, but it is worth all the effort you put in.

Running Costs

Of course, you’re wondering how much it costs to own hot tubs. The good news is that it’s not as expensive as you think. There are so many different hot tubs out there that it can be very confusing.

You’ve got to take several things into consideration, the most obvious of which are the energy and heating costs of running a hot tub.

In addition, there are several other ongoing costs to consider. For example, you should pay to get hot tubs serviced once a year. There are also numerous water care products and other consumables you’ll need to purchase.

In terms of energy running costs, good quality hot tubs should cost no more than around £30 to £40 per month, if you’re using the tub between three and four times each week.

Working out annual hot tub running costs is not quite so simple because of the number of factors that come into play. In order to give you some kind of guideline, we’ve estimated the average running costs to be between £675 and £965.

Disease Risk and Safety

While having a hot tub can bring many benefits, there are also some things you need to remember if you want to stay safe when using your hot tub.

1. The water can make you feel sick

The warm water in hot tubs is the perfect environment for bacteria to feel at home and multiply. You should avoid swallowing the water or even getting it in your mouth because the germs in the water could cause unpleasant and even life-threatening illnesses.

2. The steam can make you sick

While there’s a risk of contracting an illness such as Legionnaires’ disease by swallowing contaminated water, inhaling contaminated water vapour can also be very risky.

3. The heat can leave you feeling woozy

Hot tubs usually have a timer on them and this is for a good reason. When the water jets turn off, it’s time for you to get out and take a break.

The heat in your hot tub expands blood vessels. This makes your blood pressure drop which can be serious for people who already have low blood pressure. There is a risk of passing out and possibly drowning.

Drinking alcohol in your hot tub is equally risky. When you combine the alcohol with hot water it will lead to lower blood pressure and impair your judgement.

4. You might get a rash

Hot tub rash is a skin infection that can affect hair follicles and leave your skin feeling itchy, red, and blistered.

While a hot tub can be fun, there’s also an element of danger involved, so you should always be aware and take necessary precautions to keep yourself, your family, and your friends safe at all times.


Installing a hot tub is not a complicated process, but it can go south very quickly if you don’t know what you’re doing. Here are a few quick tips:

  1. Do your homework: Pick the best model for you and your family and choose the location wisely.

  2. Pick the perfect location: It should have a solid foundation, nearby water, power, and drainage, access to the access panel, privacy, easy access, and preferably a view.

  3. Plan the landscape around it.

  4. Get the foundations in place.

  5. Install the electrics.

  6. Wait for your hot tub to be delivered.

If you get everything ready, installing your hot tub should be a smooth and trouble-free process.

Hot Tub Accessories and Equipment

If you want to create the perfect spa experience in your own home, there are plenty of accessories and equipment you can purchase to enhance your hot spa. Here are a few ideas:

  • Hot tub cover

  • Saltwater system

  • Spa umbrella

  • Hot tub steps and handrail

  • Hot tub filter

  • Spa pillows

  • Water seats

  • BBQ

  • Floating spa butler

  • Countless different hot tub toys

  • Air blower

  • Hydro jets

With the right accessories and equipment, you might find yourself enjoying a hot spa at home, every day of the week.

How Much Does a Hot Tub Cost?

If you’re in the market for a home spa, you’ll want to know how much a hot tub might cost. Perform a basic search online and you’ll be faced with an overwhelming range of choices. Different hot tubs come in all shapes and sizes, each with its own price tag.

There is a wide range of price points, from cheap inflatable tubs that start at around £300, right up to the most luxurious models that come with a price tag of up to £25,000.

Whatever your budget, you’ll find a hot tub that won’t break the bank and will give you good value for money.

What to Look for When Buying a Hot Tub?

When you’re ready to start looking for your hot tub, there are many things to bear in mind if you want to find a hot tub that’s right for you. Here is a quick list of things you should consider:

  • How it feels: Look for a hot tub showroom that allows you to wet test models.

  • The seating capacity: Think about how many people will use your home spa and how often.

  • The power supply: Hot tubs tend to run on either a 13 amp or 32 amp power supply/

  • The seating arrangement: Do you want an all-seater or lounger hot tub?

  • The build quality: But the best quality hot tub you can afford.

  • The frame: It should be made of galvanised or stainless steel.

  • The waterproofing: the hot tub’s floor should have a waterproof membrane or material that prevents damp rising.

  • The insulation: Fully foamed is best because it will mean your hot tub costs less to run.

  • The cabinet: Choose a model made using treated timber.

  • Hot tub covers: If your hot tub has an air-tight, fully-insulated cover, your hot tub will be more energy efficient.

  • The air jets: The more jets the better if you want the best hydrotherapy massage.

  • The filtration system: Choose a model with a top-of-the-range filtration system.

  • Built-in water treatment devices: These might include ozone generators and UV systems.

  • The control panel: Look for something that’s intuitive to use.

  • The lighting: LED light will add to the ambiance while you enjoy your soak.

  • Multimedia options: Smart TVs or built-in Bluetooth speakers are nice to have.

Now you know what to look for when buying a hot tub, it’s time for you to head out and close the deal on yours.

Aqua Warehouse offers a variety of premium quality hot tubs for sale that are suitable for 2 to 7 people. Call 01245 477 400 or send us a message for a free consultation.


A good quality hot tub doesn’t come cheap. It’s therefore very important that you do your homework before you flash the cash.

In this guide, you’ll find all the information you need to help you make an informed decision. It won’t be long before you’re the proud owner of your very own home spa.


1 Comment

Jul 07

A hot tub is a luxurious water-filled basin designed for relaxation and hydrotherapy. Proper installation and maintenance are crucial for its functionality, often requiring professional plumbing services to ensure the water systems and jets are correctly installed and maintained. With expert plumbing services, you can enjoy the ultimate hot tub experience with reliable and efficient operation.



Jess Court

I'm Aqua Warehouse Groups Marketing Officer - overseeing all things news worthy in the hot tub industry, with tips and tricks that are bound to make a splash.

  • Instagram
bottom of page