What is a Kohler Class 5 Toilet?

A Kohler Class 5 flushing system is one of the most efficient and powerful toilet flushing systems available today. Developed by Kohler, a leader in bathroom fixtures and fittings, the Class 5 flush aims to provide maximum flushing performance while using minimal water. In this comprehensive guide, we’ll explore what makes Kohler’s Class 5 flush so effective, the patented technologies behind it, the water savings, and how it compares to other toilet flushing systems.

A Kohler Class 5 toilet refers to a high-efficiency toilet (HET) that is designed and engineered by Kohler to provide effective bulk waste evacuation while using only 1.28 gallons of water per flush (gpf).

To earn the EPA‘s WaterSense label and be designated as an HET, a toilet must flush at 1.28 gpf or less. Kohler‘s Class 5 toilets with a single flush of 1.28 gpf surpass this requirement.

The Class 5 specification was designated by Kohler as their most advanced class of low-flow toilet. Class 5 represents the pinnacle of their flushing technology, combining innovations in valve design, bowl geometry, and glaze to optimize every aspect of the flush.

Key features of Kohler‘s Class 5 toilets include:

• Uses only 1.28 gallons per flush (20% less than the standard 1.6 gpf toilet)
• Provides full evacuation of waste in a single flush
• Incorporates a wide 2-3/8" trapway and optimized bowl geometry
• Utilizes the AquaPiston canister flush valve for increased power and efficiency
• Engineered for optimal performance with a MaP (Maximum Performance) score of 1000 grams
• Surpasses EPA WaterSense criteria for high efficiency and water conservation

By meeting rigid performance requirements while using 20% less water than a standard toilet, Class 5 models represent Kohler’s most environmentally friendly and high-performing toilets.

To better understand the Class 5 flush, it helps to learn about the various toilet flushing systems developed by Kohler over the years. Their flush classifications include:

Class 1 – Early low-flow flush toilets made in the 1980s-90s that used 3.5 gpf or less. Offered incomplete waste removal.

Class 2 – Improved low-flow toilets made in the 1990s that used 2.5 gpf or less. Decent waste removal.

Class 3 – High-efficiency toilets launched in 1994 that used 1.6 gpf or less. Good bulk waste evacuation.

Class 4 – Advanced HETs introduced in 2010 that used 1.28 gpf or less. Excellent waste removal.

Class 5 – The latest generation of HETs offered since 2021. Uses 1.28 gpf for superior flushing performance.

Over the years, Kohler has progressively improved their flushing systems to use less water while maintaining or boosting flushing power. The Class 5 represents the current pinnacle for efficiently evacuating waste.

So what exactly makes the Class 5 flush so effective? Kohler has engineered a suite of advanced technologies to optimize every phase of the flush.

AquaPiston Flush Valve

The AquaPiston is Kohler’s patented canister-style flush valve that releases water into the toilet bowl more efficiently than old-fashioned flappers.

Inside this valve is a piston that shoots water into the bowl at a high velocity through a 360-degree opening. This creates an aggressive siphon effect and turbulence to powerfully remove waste.

The large 3" diameter AquaPiston valve allows more water to enter the bowl at once compared to standard 2" flush valves. The piston also seals tight to prevent leaks between flushes.

Optimized Trapway

The trapway is the waste passageway that connects the bowl to the sewer line. Kohler Class 5 toilets utilize an oversized trapway measuring 2-3/8" in diameter.

This wide pathway allows a higher volume of water and waste to funnel through. The glazed surface helps waste slide smoothly into the trapway for quick evacuation.

Forces of Nature

This refers to the channels inside Class 5 toilet bowls that dictate water flow during a flush. There are precision-engineered channels, called the Force of Nature, positioned around the bowl rim.

As water rushes down during a flush, these angled channels force the water into a swirling vortex that races around the bowl walls. This pulls the waste completely free before guiding it out the trapway.

Revolution 360 Swirl Flush

The Revolution 360 feature works in unison with the Forces of Nature channels. It incorporates a series of jets under the toilet rim that shoot water around the bowl in a 360-degree cleaning motion.

This creates a forceful swirling flush pattern that scrubs every inch of the bowl with each flush. By covering more surface area, the Revolution 360 provides superior bulk waste removal.

High-Efficiency Bowl Design

Class 5 toilets utilize a bowl shape engineered to maximize the flushing power of minimal water. The design incorporates a wider bowl water surface which adds more push when the siphon starts.

There is also an elongated bowl and optimized water storage between flushes. Together, these features allow complete waste removal using just 1.28 gallons per flush.

The Class 5 flush offers significant water savings compared to older toilet designs.

To put this in perspective:

• Older 3.5 gpf toilets use nearly 3x more water than a Class 5 toilet
• Standard 1.6 gpf toilets use 20% more water than Class 5 toilets

For a household of 4, switching to a Class 5 toilet can save:

• Nearly 13,000 gallons per year (compared to a 3.5 gpf toilet)
• Over 4,000 gallons per year (compared to a 1.6 gpf toilet)

The EPA estimates that if just one in every 10 homes in the U.S. installed a WaterSense labeled HET, it would save nearly 100 million gallons of water per day across the country. Kohler’s Class 5 line can help make this level of conservation a reality.

Kohler currently offers several Class 5 single-flush toilet models to choose from:

• Highline – Kohler’s most popular Class 5 toilet. Combines classic style with ultra-efficient flushing.
• Cimarron – An affordable, compact Class 5 toilet with modern appeal.
• Tresham – A unique Class 5 toilet with stately design and smoked glaze.
• Veil – Offers a sophisticated elongated Class 5 toilet with clean lines.
• Memoirs – Elongated Class 5 toilet with traditional styling and chair-height seat.

Each of these models is available in one-piece and two-piece configurations. There are also several Class 5 dual-flush toilets offered for added water conservation.

For even greater water efficiency, Kohler engineered Class 5 toilets that utilize a dual-flush system. This allows a light flush of 0.8 gpf for liquid waste or a full 1.28 gpf flush for solids.

This dual-flush design can save up to 25% more water than a standard single-flush Class 5 toilet. Kohler dual-flush Class 5 models include:

• Highline – Available as a classic two-piece or streamlined one-piece.
• Cimarron – Contemporary one-piece dual-flush toilet.
• Archer – Transitional style one-piece dual-flush toilet.

The dual-flush Class 5 toilets give homeowners and businesses increased options for conserving water. Just the light 0.8 gpf flush can be used for 70% of flushes.

Kohler Class 5 toilets range in price from $200 – $700 depending on the model. Here are some examples:

• Cimarron – Starts around $200
• Highline – Starts around $350
• Veil – Starts around $500
• Memoirs – Starts around $700

In general, Class 5 toilets cost more than standard 1.28 gpf toilets, but are competitively priced with other high-efficiency models. Many homeowners find the water savings of an EPA WaterSense Class 5 toilet offset the slightly higher upfront investment over time.

Here are some of the top benefits of choosing a Kohler Class 5 toilet:

Saves Water – Uses up to 20% less water than a standard 1.6 gpf toilet. Significant water conservation.

Superior Flushing – Innovative system provides full bowl evacuation in just one flush.

High Efficiency – Meets EPA criteria for WaterSense labeled toilets.

Powerful Performance – Wide flush valve, optimized bowl design, and precision water channels provide maximum efficiency.

Dual-Flush Options – Some models offer dual-flush choice of 0.8 gpf or 1.28 gpf for added water savings.

Quiet Operation – Flushing is designed for minimal noise disruption.

Easy Maintenance – Two-piece models allow for quick replacement of individual components if needed.

Trusted Brand – Kohler is known for durable, high-quality bathroom fixtures.

For homeowners and businesses seeking an eco-friendly toilet that doesn’t compromise performance, Kohler’s innovative Class 5 line offers compelling benefits.

How do Kohler Class 5 models compare against other manufacturers’ Class 5 toilets? Here’s an overview:

• American Standard – Also offers a range of effective Class 5 toilets equipped with powerful flush valves and large trapways. Tend to cost slightly less than comparable Kohler models.

• Toto – Well-known for their efficient double cyclone flushing system and quiet operation. Priced similarly to Kohler Class 5 toilets. More contemporary styling.

• Woodbridge – Budget-friendly Class 5 toilet option. Components may not be as durable as more expensive brands over the long-term.

• Niagara – Specializes in ultra-high-efficiency Stealth toilets that use only 0.8 gpf. Very affordable but require more frequent double flushing.

While other brands make high-performing Class 5 toilets, Kohler stands out for its broad range of styles and innovations like the AquaPiston valve. Owners can expect long-lasting durability from the Kohler brand.

Kohler uses Class 6 to designate high-efficiency toilets that go beyond Class 5 models to deliver even greater water conservation.

Class 6 toilets use an ultra-low 0.8 gpf but require a two-flush system to handle solid wastes. This dual-flush approach does offer maximum water savings. However, owners may find the need to routinely flush twice can be inconvenient.

Here is a quick comparison between Kohler Class 5 and Class 6 toilets:

Class 5

• 1.28 gpf single flush
• Fully evacuates bowl in one flush
• AquaPiston canister flush valve
• Meets EPA WaterSense standards

Class 6

• 0.8 gpf light flush
• 1.28 gpf full flush
• Requires double flushing for solids
• Exceeds EPA WaterSense standards

For the best combination of flushing performance, convenience, and significant water savings, most homeowners find the single-flush Class 5 models to be the ideal choice. The Class 6 dual-flush can offer slightly more conservation for those wanting to maximize every bit of water savings possible.

Kohler’s Class 5 flushing system is designed to efficiently and fully clear bowl waste in just one flush. This is thanks to the optimized bowl geometry, the power of the AquaPiston valve, and precision-engineered water channels that all work together to create the strongest possible siphon effect using minimal water.

The Class 5 system has been performance tested and proven capable of moving large mass waste loads. In fact, Kohler submits their Class 5 toilets to Maximum Performance (MaP) testing, which is the industry standard for evaluating the waste removal effectiveness of low-flow toilets.

The independent MaP testing protocol involves repeatedly flushing a mix of faux waste and soiled test media down the toilet. The Kohler Class 5 toilet models consistently score 1000 out of 1000 grams, meaning they fully evacuate all test media with just a single 1.28 gpf flush. This confirms the superior bulk waste clearing ability of the Class 5 flushing technology.

Here is a quick recap of the benefits and downsides of the Kohler Class 5 flushing system based on expert analysis and customer experiences:

PROS

• Delivers full bowl clearing power with only 1.28 gpf
• AquaPiston provides strong siphon during flush
• Prevents clogs with wide trapway design
• High-efficiency meets EPA criteria
• Easy-to-clean bowl design
• Most backed by strong Kohler warranty

CONS

• Higher price than standard 1.6 gpf toilets
• Some noise associated with powerful flush
• Occasional need to double flush due to low gpf
• Must use high-efficiency toilet papers

Overall, the Class 5 system consistently ranks among the top-performing single-flush high-efficiency toilets. It hits the sweet spot of moderate water savings and maximum bowl clearing effectiveness in a single flush. For households looking to conserve water without sacrificing power or convenience, Class 5 models are an excellent choice.