How to Build a
Quality Whirlpool Bath

The following manufacturing information will take you step-by-step through the manufacture of an acrylic whirlpool bath. It is our intent to inform and educate you not only about the manufacturing process but some of the differences in components and manufacturing that can be the difference in purchasing a quality tub or one that will pose problems. Please click the faucet icon next to the topic that interests you.

Step 1: Acrylic

All of our whirlpool baths are made from durable, non-stick, stain-resistant acrylic. The thickness of the acrylic sheet that is used in making a tub is of the utmost importance.

The thickness of the acrylic sheet depends on the size and depth of the tub mold. Picture 1 shows the difference between a sheet used by Watertech (light color sheet) vs. our competitor's thin (dark color) sheet.

Picture 1: Watertech acrylic thickness (left) vs. Competitor acrylic
thickness (right).

By using thick .157 or .125 (depending on the depth and size of the tub) acrylic, Watertech ensures that each tub shell (Picture 2) that comes out of the mold will meet and exceed industry standards for thickness.

Picture 2: Removing the acrylic tub shell after the molding process.

On deeper tubs such as the Watertech Model 6032 Ultra, a .157 thick sheet is used due to the 23-inch depth of the tub. Each Watertech tub removed from the mold has the required thickness necessary to ensure a durable, high quality tub from the bottom surface to the top of the deck (Picture 3).

Picture 3: Tub shell after being removed from mold.

Our competitors often use thin .08 sheets of acrylic which leads to thin spots when the acrylic is stretched in the molding process. Thinner sheets of acrylic are used because it saves the manufacturer money and is usually something the customer never thinks to ask about. Having the required acrylic thickness all over the tub ensures a strong tub that if scratched can easily be buffed or sanded out which eliminates any costly repairs.

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Step 2: Molding Process

Acrylic tubs are made by pulling (known in the industry as vacuum forming) a heated acrylic sheet into a tub mold (Picture 4).

Picture 4: Watertech tub mold.

After the correct thickness of acrylic sheet is selected, Watertech's professional staff places the acrylic sheet onto the top of the mold (Picture 5) which is attached to a vacuum forming system. The sheet is inspected for any defects or blemishes then clamped to the tub mold.

Picture 5: Attaching the acrylic sheet onto the tub mold.

The acrylic sheet attached to the mold is then moved under a ceramic element oven (Picture 6).

Picture 6: Moving the tub mold with the attached acrylic sheet under the oven.

The oven heats the acrylic uniformly to 400 degrees at which point the hard acrylic sheet is transformed into a soft, stretchable, jello-like condition. At this point, the vacuum system is turned on and the sheet is pulled into the mold (Picture 7). As the sheet is pulled, it stretches, which is why using the proper thickness of acrylic is so important. Thin .08 sheets stretch too thin near the floor of the tub, especially in the corners.

Picture 7: Tub after vacuum forming pulls acrylic sheet into the mold.

Once the molding process is complete, the tubs are removed from the heat and allowed to cool to the proper temperature. The vacuum is then turned off and the formed acrylic tub shell (Picture 8) is taken from the mold, inspected and stored in a waiting area before going into the fiberglass chopping booth.

Picture 8: Removing the vacuum formed tub shell from the mold.

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Step 3: Fiberglass Backing

The tub shell is placed on a special holding fixture and taken to the fiberglass spray booth. A mixture of polyester resin, fire retardant material, fiberglass roving and a catalyst are then sprayed (chopped) onto the back of the tub shell by a "chopper gun" (Picture 9).

Picture 9: Tub shell being sprayed with the chopper gun creating a fiberglass backing.

Approximately 3/8" to 1/2" of material is applied, with slightly more applied to the tub floor bottom. This fiberglass mix is allowed to harden and bonds with the acrylic shell to add substantial durability and strength to the tub.

Some manufacturers cheapen their mix by adding large amounts of powdered calcium carbonate to their mix. This reduces the expensive polyester resin in the mix - yet another cost cutting measure that you will never know about. Using the cheaper mix means you receive a less durable tub. Often, this mix will be thicker than 1/2" which leads some consumers to believe they have a better and stronger tub - but in reality a filled thick coating on the tub is much weaker than a thinner, properly mixed fiberglass coating.

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Step 4: Structural Steel Base

While the fiberglass resin is being applied to the bottom and sides of the tub shell, Watertech installs a structural, rust-proof steel base to the bottom of the tub/floor (Picture 10).

Picture 10: Watertech is the only manufacturer to use a structural steel base that levels the tub and is used to mount the pump and motor.

This structural steel base further strengthens the bottom of the tub, levels the tub, and provides for a steel motor/pump mounting platform. Watertech is the only manufacturer to incorporate this structural steel base into each and every tub. This base helps eliminate pump/motor vibration and ensures that the pump/motor stays in place and operates quietly (Picture 11)

Picture 11: Placement of pump and motor on the structural steel base.

Other manufacturers use wood and plastic bases to support the motor/pump. (Picture 12) The wood and plastic often flexes or swells where the motor and pump are installed which leads to vibration, noise, and possible leaks. All whirlpool baths should be embedded in cement mortar to ensure a rigid tub floor. Wood and plastic bases don't allow for mortar under the tub which leads to a soft, flexible, tub floor. Watertech's steel base allows for mortar installation under the tub floor.

Picture 12: Competitor wooden tub base with small universal pump and motor.

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Step 5: Trimming & Plumbing Assembly

Once the sprayed fiberglass resin material cures, it becomes a hard durable fiberglass material and the tub is then ready to be removed from the spray booth. The tub is then taken to an area where an automated trim saw is used to cut off all excess material along the edges of the tub.

Once trimmed, the tub is ready to be taken to the plumbing assembly area (Picture 13).

Picture 13: Tubs that have been trimmed and ready for plumbing process.

Watertech's master plumbers then go to work, drilling holes into the acrylic tub that will be used for installation of the high pressure jet system and other parts (Picture 14).

Picture 14: Holes drilled for installation of jets and hardware.

After all of the jets and other components are installed, the tub is again checked for any blemishes or defects (Picture 15).

Picture 15: Jet installed in tubs. Notice bend of PVC Schedule 40 Pipe and automatic air intake (pipe extending vertically from the jet).

The next step in the manufacturing process is one of the most important - the installation of the pipe system. Watertech uses only Rigid Schedule 40 PVC piping. The rigid pipe is heated so it can be curved and properly bent so that the piping system always allows for 100% drainage which ensures a clean, sanitary whirlpool system with no sags or low spots that can trap dirty bathwater (Picture 16).

Picture 16: Properly heated and bent Rigid Schedule 40 pipe. Use of this pipe allows for 100% drainage of your system - leaving no dirty bathwater in your pipes after the tub is turned off.

Many companies use flexible pipe which allows them to stay away from the costly and time consuming method of having to heat Rigid Schedule 40 PVC pipe and bend it before placing it on the tub. They simply cut a piece of "flex pipe" from a roll and stick it between the jets. But, this process produces a tub that has pipes that sag - meaning low spots in your system that traps dirty bath water which is unsanitary (Picture 17).

Picture 17: Competitor tub with flex piping. Notice the sagging lines which can trap dirty bath water when your system is cut off

Remember, Rigid Schedule 40 PVC meets all plumbing and housing codes and is the pipe of choice that you should demand in your tub. Flexible pipe meets no plumbing or housing codes (you can't plumb your house with it) and over time, flex pipe deteriorates, becomes brittle (much like a garden hose) and develops cracks which leads to leaks.

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Step 6: Pumps & Motors

Watertech Whirlpool baths come equipped with either 2 or 3 HP pumps. Some models have dual pumps. Check our catalog or website for size and location of pumps for all models. Each pump carries a LIFETIME WARRANTY. If a pump ever fails simply call and a replacement will be shipped at no charge. Pumps are 100% self draining with quick disconnect unions and electrical chord for easy servicing. Pump upgrades are offered on most models. Two speed switches are available for all pumps that will allow your pump to operate on either a high or low pressure setting with a touch of the finger. Watertech engineers all its tubs to that the pump's performance equals jet output to ensure maximum pressure and flow. Proper pump size ensures quiet operation, no vibration and maximum hydrotheraphy at each jet.

All of our pumps are attached to the Watertech structural steel base (Picture 18.) Watertech is the only manufacturer to use a steel base which ensures the pump will stay in place -- eliminating noise and vibration which can cause leaks and provide a less than enjoyable bathing experience.

Picture 18: Pumps attached to structural steel base.

Manufacturers that use a wood or plastic base to attach the pump do not provide a solid base which can lead to increased vibration, noise, and possible leaks.

Because wood has a tendency to warp or swell in a high moisture environment, the screws that attach the pump and motor to the base can work loose - creating numerous problems. (Picture 19).

Picture 19: Competitor's pump placed on a wooden base. This type of base can cause vibration, noise and possible leaks in your tub.

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Step 7: Jet System & Air Injection System

In place of standard industry regular bath jets, Watertech uses only high performance Ultra Spa Jets. Each jet is individually controllable, allowing you to regulate the water pressure and direction of flow. An exhilarating 16-gallons of water per minute is produced by each jet - unlike the average whirlpool jet which yields only 4-6 gallons per minute. The Ultra Spa Jet is 100% self-draining, just like our rigid plumbing system, for a safer, more hygienic bathing environment (Picture 20).

Picture 20: Watertech's adjustable high pressure spa jet provides16-gallons per minute of pressure. The competitor's non-adjustable jet provides only 6-8 gallons per minute of pressure.

In addition, Watertech is the only manufacturer to use automatic air injectors on all its tubs. The air injectors produce a constant air/water mixture at each jet - unlike other manufacturers' noisy air controls which allows the first jet in the whirlpool system to have more pressure than the last jet in the system. Air controls also produce a whistling sound as air is drawn into the whirlpool system. Watertech always strives to use the newest proven technology available (Picture 21).

Picture 21: Vertical air injection pipe (vertical pipes in picture above) available only at Watertech. This pipe allows for an equal mix of air and water for each jet in the system.

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Step 8: Pressure & Leak Testing

Each Watertech tub goes through several quality control checks throughout the manufacturing process. The last quality check involves complete water pressure testing and checking for leaks. Once our plumbers have inspected the entire pipe, jet, pump, and motor system, the tub is taken to a final testing station where it is filled with water, the system turned on, and a final check is made for proper performance and any leaks in the pipe system (Picture 22).

Picture 22: Each Watertech tub is filled and checked for leaks and pressure testing before shipment.

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Step 9: Packing & Shipping

The final step in the manufacturing process is packaging your tub for shipment. Watertech uses a heavy duty corrugated shipping container and places protective styrofoam blocks on the bottom of the container (Picture 23).

Picture 23: Placing the protective styrofoam strips in the bottom of the shipping container.

The tub is then placed on top of the protective styrofoam blocks and a piece of protective plastic is attached to the top of the tub. Once the protective layer of plastic is in place, Watertech places more protective styrofoam "clips" along the sides and top of the container, providing complete protection for your tub (Picture 24).

Picture 24: Placing the protective styrofoam "clips" along the sides and top of the tub in the container.

The lid of the container is placed over the tub and secured. Now the tub is ready to be shipped safely and securely to you. (Picture 25).

Picture 25: Styrofoam-packed whirlpool tub in shipping container, ready to be shipped to you — with no damage!

Most manufacturers ship their tubs in wooden crates, on pallets, or in boxes — with little or no protection. This type of shipping can cause the tub to shift during shipment, leading to cracks on the acrylic surface, leaking pipes, or damage to the pump and/or motor.

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Why We Want You To Know This

We have taken the time to show you the various steps in the manufacturing of a Watertech acrylic whirlpool tub so that you can make an informed buying decision.

We realize that people who put a whirlpool in their home don't want to purchase a whirlpool only to find out at a later date that they have bought a tub that is of poor quality. We all realized that once a bath tub is installed, it is a permanent part of your home — not easily or inexpensively changed.

By showing the public the various steps and materials that go into a quality whirlpool tub, we feel that the consumer can now avoid the pitfalls of buying only on price. They can now determine which manufacturer offers true value — and remember — buying a brand name or settling on the cheapest price doesn't always equate with quality.

Watertech sells one of the finest whirlpool baths on the market. Buying an inferior quality whirlpool (sometimes at a cheaper price or sometimes at inflated high prices with a brand name) doesn't need to be a part of one of the most important investments in your life — your home.

We thank your for reviewing the information on our web site and we hope it has been helpful as you decide on the purchase of your whirlpool bath. If we left anything out, or if you would like further information, please feel free to e-mail us at sales@watertechtn.com or call us toll free at 1-800-289-8827. Our office hours are Monday-Friday 8 a.m. - 5 p.m., and Saturdays, 8 a.m. - Noon.

For over 20 years, Watertech has been providing new and existing homeowners with one of the finest whirlpool baths on the market. Our philosophy of treating others as we would want to be treated has served our company well.

We know you will thoroughly enjoy your new Watertech whirlpool bath!

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Examples of How to Build Whirlpool Tub Framing

Below are some examples of tub framing (Picture 26).

NOTE: Because some of our models are irregular in shape and size, Watertech does not recommend framing and/or installing finish materials until you receive the tub. You do so at your own risk. Watertech will not be responsible for problems that may arise due to improper framing.

Picture 26: Examples of tub framing.

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Hometech produces quality products under the tradenames WATERTECH Whirlpool Baths,
Spas and Accessories and WEATHERGUARD Steel Structures, Car and Patio Covers.

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