When you imagine a hot tub, you probably picture a traditional model with a glossy acrylic shell (the part you sit in) and rustic wood sides.
But did you know there's a more eco-friendly and cost-effective option, that can give you practically all of the same benefits?
Unlike acrylic spas, rotomolded or rotationally molded spas are made from a high-density thermal plastic. On average, they run smaller than acrylic models and typically have fewer jets and features, but they are also more lightweight, durable and affordable.
This article will cover everything you need to know about rotomolded hot tubs: how they're made, pros and cons to consider, and which brands to look at for the best quality rotomolded spas.
How are rotomolded hot tubs made?
Rotomolded spas get their name from the manufacturing process: high-density polyethylene (HDPE) resin is poured into a spa-shaped mold, which is then slowly rotated to evenly coat the inside of the mold. When it dries, what's left is a plastic one-piece hot tub shell.
You can see some footage of the process here:
Rotomolded vs Acrylic spa comparison
Let's take a look at the differences between rotomolded and acrylic spas, to help you decide which is the better choice for you.
The first thing you'll notice is that rotomolded spas can look different.
Whereas acrylic spas have glossy, high-shine interiors and contrasting wood cabinets, many rotomolded spas are one main color (usually gray, beige or brown) and have the same matte texture inside and out.
Here's how a conventional acrylic tub looks:
And here's a rotomolded spa:
Some people dislike the aesthetics of rotomolded hot tubs, but I think they can actually look great—it all comes down to how you style the area around the spa.
What's more, this single-color, matte look mostly applies to budget models these days.
In modern, high-end rotomolded spas, manufacturers have developed ways to achieve a smooth, acrylic-like finish for the shell. They then use contrasting synthetic wood panels on the sides to achieve the look of a more traditional spa.
A good example of this is the Dream Maker Spas Crossover Collection:
Compared on price alone, rotomolds are the clear winner: most rotomolded spas fall in the $2,000-$6,000 price range, but for a quality acrylic spa, you can expect to pay anywhere from $5,000-$16,000+.
Why the difference?
Rotomolded spas are simpler (and therefore cheaper) to produce. They're made with fewer materials, and more of the manufacturing process can be automated, which means lower labor costs, and therefore lower prices.
On average, rotomolded hot tubs are smaller than their acrylic equivalents.
You can find acrylic spas for up to 9 people, but the largest rotomolded models have a maxiumum capacity of 6-7. Many acrylic spas are 36" deep, whereas there's a wide selection of rotomolded spas available at 32" or less.
That extra depth might be welcome if you're tall, but if you want a shallower hot tub for kids, shorter bathers or easier access—or if you need to get your spa through a gate or door—you'll have a lot more options in the rotomolded hot tub market.
Although rotomolded spas are generally smaller, their size and materials mean they're also lighter. At around half the weight of a conventional acrylic spa, rotomolds therefore have the advantage that they're much more portable.
Traditional spas are heavy and delicate—you can't generally expect to just shift a 600 lbs spa around your backyard. But with a 300 lbs rotomold, relocating it becomes surprisingly possible with two adults and a hand truck.
This is also good to bear in mind if you move a lot and want a spa you can take with you. Renting, or in the military? A rotomolded spa could be an excellent choice.
Most rotomolded spas are in the 'plug-n-play' category, which means they are designed to be plugged into a standard 110V outlet. Acrylic spas generally need a 220V outlet, which means hiring an electrician if you don't have one already available.
If you do run a rotomolded spa on 110V, be aware that you can only run a single pump, which means you can't use the heater and jets at the same time. The result is that while you're in the tub with the jets on, it won't be able to maintain its temperature, so the water will gradually cool.
In practice, this usually happens slowly enough that it isn't too noticeable (especially for short spa sessions), but it does mean rotomolded spas are not generally suited to very cold temperatures.
Did you know? It's also possible to convert most rotomolded spas to work with 220V, in which case you can run both jets and heater at the same time, just like with an acrylic spa.
Features are something some spa owners care about more than others. While some people want a futuristic spa with fountains and waterfalls and lights and all the latest tech, others would rather have a basic tub for a simpler soak.
While rotomolded spas generally do come with some lights and basic water features, they'll be less fancy. And with less power, they also have fewer (and gentler) jets.
Check out my ultimate guide to spa lighting which features several smart ideas for adding extra lights if your spa doesn't have enough.
So if you're looking for the most advanced hydrotherapy experience available, you won't find that in a rotomolded spa.
Rotomolded tubs are strong, durable and robust. They excel at withstanding the kind of use that could damage an acrylic spa, which makes them a great choice if you have kids, and also a solid option if you're looking for a spa to put in a vacation rental property.
Where acrylic spas can crack, split, peel, or even rot in the case of wood, rotomolded tubs don't have any of these problems.
Their unibody construction means they can even flex up to a couple of inches without breaking (though you should still always set them on a level surface to minimize warping).
Did you know? A unibody shell is sealed all the way around, with a solid one-piece base under the spa. While you can unfortunately get rodents nesting in the insulation of a traditional acrylic spa, there's no way for mice, rats or larger pests to find their way inside a rotomolded shell.
Most manufacturers offer 5-year+ warranties on the shells of rotomolded spas, with some even having lifetime warranties.
Although rotomolded spas are generally well insulated, the plastic shell can be a little less energy efficient than a quality acrylic spa.
However, unless you live in a very cold climate, the difference to your electricity bill will be small enough that you'll generally still save more overall by buying rotomolded, thanks to the much lower initial cost of the spa.
A single surface material of hardwearing plastic makes rotomolded spas very easy to care for. When it's time to drain the spa for cleaning, you can just wipe the whole thing down with a damp cloth and some bleach or cleaning spray—no special treatment needed to refinish fancy wood sides, or avoid damaging the shell.
Rotomolded spas are water resistant all over, so you don't have to worry about the outside getting wet or rotten in the rain or from splashing during use; simply hose it down to remove any dirt.
What's more, the plastic material of rotomolded spa shells is fully recyclable. This means your spa can be made into something else when you're done with it, which is a nice eco-friendly touch.
Popular rotomolded spa brands
Today, many spa manufacturers offer at least one rotomolded model. But there are a few that specialize in this type of construction:
Strong Spas make some very durable rotomolded hot tubs, with innovative touches like integrated ice bucket, steps and cover, designed to fit perfectly and last for the lifetime of the spa.
Most of their spas are designed to be run on 220-240V power, although they do offer some plug-n-play models in the rotomolded DuraSport Series.
Tuff Spas are another solid, resilient range of spas with a similar integrated cover, which turns into a handy shelf/bar when the spa is in use.
All Tuff Spas come ready to plug into a standard 110V outlet, with the option to convert to 220V if you prefer, plus they offer a lifetime warranty on the shell.
Freeflow offer 10 unique plug-n-play models. Although their more basic spas are limited in color choice, their Premier Series feature synthetic wood cabinetry for a more traditional look, but with the durability of a rotomolded spa.
Every Freeflow Spa is backed by a 5-year structure and shell/surface warranty.
Dream Maker is one of the world’s largest manufacturers of rotomolded spas, and has been a leader in the space since introducing this type of manufacturing to the spa industry in 2001.
Their spas feature a proprietary material that gives them an acrylic-like smooth texture while retaining the durability and strength of a rotomolded spa.
AquaRest offer a budget-friendly line of rotomolded spas. Their hot tubs are on the smaller side, with the largest accommodating up to 6 people.
All models come with basic color choices and a marine-grade vinyl cover, LED Backlit Waterfall, 1.5 HPR energy-efficient pump, full foam insulation, and a 5-year shell warranty.
Should you buy a rotomolded spa?
As you can see, rotomolded spas can be a solid choice for almost everyone. But they could be especially good for you if any of these apply:
- You need your hot tub to be kid-proof
- You're looking to spend $6,000 or less
- You don't like powerful jets, and just want to soak in hot water
- You don't care about the fanciest features or cutting-edge technology
- You'd prefer a shallower tub (32" or less)
- You need to get the spa through a gate or door
- You're looking for a spa to put in a vacation rental
There are also reasons rotomolds might not be the right choice, of course. Consider sticking with acrylic if this sounds more like you:
- You live in a very cold climate
- You want a luxury spa with all the latest features
- You're after the most advanced hydro-massage jet experience
- You want a very large hot tub (for 8 or more people)