Home » The Pros and Cons of Dual Flush vs Single Flush Toilets

The Pros and Cons of Dual Flush vs Single Flush Toilets


The choice between a dual flush or single flush toilet is an important one that can impact your water usage, utility bills, and bathroom experience. Both options have advantages and disadvantages to consider before deciding which is best for your home. This guide examines the key differences between dual flush vs single flush toilet and provides tips for choosing the right model.

How Dual Flush Toilets Work

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Dual flush toilets have two flush buttons that allow you to choose between a full or partial flush. The full flush uses 1.6 gallons of water and is designed to clear solid waste. Meanwhile, the partial flush uses just 0.8-1 gallon of water and is intended for liquid waste only.

By giving users a choice between two flush volumes, dual flush toilets optimize water usage. Liquids don’t require as much water flow as solids to be flushed away effectively. With a dual flush design, you avoid wasting water by using a full flush every time.

Benefits of Dual Flush Toilets

dual flush vs single flush toilet
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There are several compelling benefits that make dual flush toilets a popular choice:

Saves Water

The primary advantage of dual flush toilets is water savings. On average, choosing a dual flush toilet can reduce your water usage by 25-60% compared to a traditional single flush toilet. The water savings come from the availability of a partial flush for liquids.

Lowers Utility Bills

By using less water, dual flush toilets also lead to lower utility bills. Your sewer charges are generally based on your water usage, so using less water saves you money on your monthly bills. The water savings from a dual flush toilet typically provides a return on your investment in 1-2 years.

High Efficiency

In addition to the dual flush feature, many of these toilets utilize other high-efficiency designs. This includes a wide, fully-glazed trapway that prevents clogs and allows waste to exit smoothly. Dual flush toilets are also gravity-fed, providing strong siphon flushing action without requiring pressure.

Quieter Operation

The dual flush system provides a quieter flush. The partial flush makes less noise than a full single flush. Dual flush toilets also re-fill the tank more quietly due to their efficient tank and valve design.

Comfort Height Seating

Many dual flush toilets feature a chair-height elongated bowl and comfort height seating. This matches the height of a standard chair to make sitting down and standing up easier for most adults. The elongated bowl also provides added room and comfort.

Potential Drawbacks of Dual Flush Toilets

dual flush vs single flush toilet
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While dual flush toilets have significant water-saving benefits, there are a few potential drawbacks to be aware of:

Higher Upfront Cost

Dual flush toilets typically cost more than a basic single flush toilet. Expect to pay $200-500 more for a dual flush model. While the water savings provide a return on investment over 1-2 years, the higher upfront cost is something to factor in.

Learning Curve

Using a dual flush toilet properly requires training yourself and others to press the right button for solids vs liquids. If the partial flush button gets pressed frequently for solid waste, the water savings benefits will diminish. Toddlers and guests may also need guidance on how to use it correctly.

Possible Reduced Flushing Power

To deliver ultra-low 1 gallon per flush performance, some dual flush models compromise on fully clearing waste with the partial flush. Users report occasionally needing to do a double flush which reduces expected water savings.

Smaller Trapway

While wider trapways prevent clogs, some dual flush toilets have a trapway that is slightly more narrow compared to single flush models. This can lead to a somewhat increased risk of clogs from large waste.

Noisy Valves

Some dual flush toilets have flappers inside the tank that make an audible clicking or rattling noise when they close after a flush. This can be avoided by selecting a quiet fill valve design, but it is a potential annoyance.

How Single Flush Toilets Work

dual flush vs single flush toilet
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Single flush toilets have one flush setting that uses the same amount of water every time. In the past, this was usually 3.5 gallons per flush (GPF) or more. However, modern high-efficiency single flush toilets typically use just 1.28 GPF or 1.6 GPF.

They work by relying on gravity and precision engineering to generate a strong siphon during the flush. This clears the bowl efficiently with a single preset water volume rather than offering a choice between two volumes.

Benefits of Single Flush Toilets

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While not as water efficient overall as dual flush models, single flush toilets provide their own pros:

Lower Cost

With a simpler single flush tank design, these toilets typically cost $100-300 less than a dual flush toilet. This makes them more budget friendly, especially helpful if you need to purchase multiple toilets.

Simple Operation

There are no buttons to push or choices to make with a single flush toilet. Users just flush as needed without worrying about partial vs full flushes. This simplicity makes them ideal for households with young children or elderly residents.

Powerful Performance

Some dual flush models compromise on power with the partial flush option. Single flush toilets are engineered to clear waste, paper, and debris with just 1.28 or 1.6 gallons per flush. This provides confidence with each flush.

Fewer Parts

With just one flush setting, single flush toilets have fewer inner tank parts that can wear out or lead to leaks. Dual flush mechanisms provide more that can go wrong down the line. The simplicity of a single flush toilet improves reliability.

Quiet Operation

Without dual flush valves and mechanisms, single flush designs avoid the potential for noisy operation and rattling. As long as you purchase a quiet fill toilet, operation will be nearly silent.

Drawbacks of Single Flush Toilets

dual flush vs single flush toilet
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While simpler and more affordable, single flush toilets have some limitations:

Uses More Water

Without a low-flow liquid flush option, single flush toilets use significantly more water for liquid waste removal. This leads to higher utility bills over time. High efficiency 1.28 GPF models help close the gap, but dual flush toilets still conserve more water overall.

Not ADA Compliant

To meet Americans with Disabilities Act (ADA) requirements for public restrooms, toilets must provide a maximum 1.28 GPF flush. Most single flush toilets use 1.6 GPF, making them non-compliant. Dual flush models can meet ADA regulations with the partial flush.

Less Durable Flushing

The higher water usage of single flush toilets causes more wear and tear on toilet valves, flappers, and seals over time compared to dual flush models. Higher flow damages components faster, shortening the functional lifespan.

Not WaterSense Certified

To earn EPA WaterSense certification, high efficiency, and performance, toilets cannot exceed 1.28 GPF. Single flush toilets using 1.6 GPF do not qualify. Dual flush models are commonly WaterSense certified due to the low-flow partial flush option.

Lower Water Savings

While technology enhancements have improved their efficiency, single flush toilets still save substantially less water than dual flush models. If water conservation is your priority, dual flush provides superior savings.

Key Factors in Choosing Dual Flush vs Single Flush Toilet

When deciding between dual and single flush toilets, keep these key considerations in mind:

  • Water Bills – Dual flush saves 25-60% more water which directly lowers your utility bills. The savings often justify the added upfront cost.
  • Household Size – Large households with high toilet usage will maximize the water saving benefits from dual flush models. The savings have less impact in a 1-2 person household.
  • User Training – Dual flush requires training users to choose the right flush setting. This can be a challenge in households with multiple residents or guests.
  • ADA Compliance – Dual flush 1.28 GPF partial flushes allow these toilets to meet ADA requirements. Single flush models using 1.6 GPF are not ADA compliant.
  • Noise Level – Dual flush mechanisms can add noise but choosing a quiet fill valve style can minimize this. Single flush toilets are simpler and quieter overall.
  • Efficiency Importance – If maximizing water efficiency is crucial for you, dual flush models are significantly more efficient than modern 1.6 GPF single flush toilets.
  • Budget – Single flush toilets cost $100-300 less upfront. Dual flush models carry a price premium but the water savings provide an ROI in the first 1-2 years.

The Bottom Line

When choosing between dual and single flush toilets, the dual flush models clearly save more water and reduce utility bills faster thanks to the low-flow liquid flush setting. However, single flush toilets can provide reliable flushing performance at a more affordable upfront cost.

Carefully examine your priorities in terms of water efficiency vs budget, training users on proper operation, and noise levels. This will determine whether a dual flush or single flush toilet makes the most sense for your particular home and family. Either option provides a significant efficiency upgrade from outdated 3.5+ GPF toilets.

Frequently asked questions about dual flush vs single flush toilets:

What is the main difference between a dual flush and single flush toilet?

The key difference is that dual flush toilets have two flush buttons allowing you to choose between a full flush (1.6 gpf) to clear solids or a partial flush (0.8-1.0 gpf) just for liquids. This optimizes water usage. Single flush toilets use a preset flush volume (usually 1.6 gpf) every time.

How much water do dual flush toilets save compared to single flush?

On average, choosing a dual flush toilet can reduce water usage by 25-60% compared to a standard 1.6 gpf single flush toilet model. The water savings comes from the availability of the lower flow liquid flush option.

Are dual flush toilets more likely to clog than single flush toilets?

Dual flush models are not necessarily more prone to clogs. Wide, fully glazed trapways in many dual flush toilets prevent clogs just as well as single flush models. Some dual flush toilets even have a larger trapway than standard single flush toilets.

Do you have to replace the whole dual flush toilet if just the flush mechanism breaks?

No, the tank assembly with the dual flush buttons and flushing mechanisms can be repaired or replaced independently without replacing the entire toilet. This provides cost savings compared to replacing the whole unit.

Which type of flush toilet is better for households with kids?

For households with young children, a single flush toilet may be preferable. The simple operation reduces the need to train kids on choosing the right flush setting. Dual flush models work well for older kids who understand the solid vs liquid flush concept.

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