What Are Gallons Per Flush? - Kitchen Cabinets

Introduction

Gallons per flush (GPF) is an important measurement to understand when shopping for new toilets. It refers to how many gallons of water a toilet uses when it is flushed. Over the years, advancements in toilet technology and federal regulations have led to dramatic reductions in water usage with each flush. Understanding GPF can help you choose a high-efficiency, water-saving toilet that meets your needs while being economical and environmentally friendly. In this comprehensive guide, we will answer the question “What are gallons per flush?” while exploring GPF standards, calculating flush volumes, comparing toilet types by GPF, and providing tips for choosing the right toilet based on gallons per flush.

What Is Gallons Per Flush?

Gallons per flush is the amount of water, measured in gallons, that a toilet uses to flush away waste with each flush. The GPF measurement accounts for all of the water used in the flush, including the water that fills the toilet bowl and the additional water used when you press the flush handle or button.

Some key things to know about GPF:

GPF measures the total water used per flush, not just the water that enters the bowl.
The lower the GPF, the less water is used per flush.
Federal regulations have mandated lower GPF levels over time to increase water efficiency.
Most modern toilets have a GPF of 1.6 or less. High-efficiency models can have a GPF as low as 0.8.
Knowing a toilet’s GPF helps compare water usage across different models.

GPF is always measured and disclosed by the toilet manufacturer. When shopping for a toilet, check the GPF rating and use it as a factor in choosing the most water-efficient model for your needs and budget.

Brief History of GPF Standards

For much of the 20th century, most toilets had a GPF of 3.5 gallons or more. However, environmental concerns and water shortages led to new federal laws mandating lower GPF levels starting in the 1990s. Here is a quick overview of the GPF standards over time:

Pre-1980s – Older toilets used 5-7 gallons per flush or more. No GPF standards existed.
1980s – 3.5 GPF became the industry standard. Some early low-flow models were 1.6 GPF.
1994 – The Energy Policy Act set a maximum GPF of 1.6 for all new toilets.
2014 – The WaterSense program set a 1.28 GPF standard for high-efficiency toilets.
2021 – Current law mandates a maximum GPF of 1.6, but most new models are 1.28 GPF or less.

So in recent decades, the average GPF has dropped dramatically from over 5 gallons to 1.6 gallons or lower. Any toilet sold today will have a significantly lower water usage than older models.

Calculating Toilet Water Usage Based on GPF

You can use the GPF rating to calculate approximately how much water your toilet will use:

Total water used = Gallons per flush x average flushes per person per day

For example, if a toilet has a GPF of 1.28 and is used 5 times per day by one person:

1.28 GPF x 5 flushes = 6.4 gallons/day

For a family of four using that toilet 15 times per day:

1.28 GPF x 15 flushes = 19.2 gallons/day

As you can see, GPF adds up fast, especially for frequently used toilets. Multiplying by the number of users and flushes provides useful estimates for daily, monthly, and annual toilet water consumption.

Comparing GPF of Different Toilet Types

There are two main toilet types available today: gravity-flush and pressure-assisted. Within these types, models range from high water usage to ultra high-efficiency based on their GPF:

Gravity-Flush Toilets

Gravity-flush toilets rely on the natural downward flow of water to siphon waste into the sewer line. Here are the GPF ranges:

Standard 1.6 GPF – Entry-level gravity flush toilets. Similar water usage to pre-1994 models.
High-Efficiency 1.28 GPF – An improvement over 1.6 GPF but not the most water-efficient choice today. Qualifies for EPA WaterSense certification.
Ultra High-Efficiency 0.8-1.1 GPF – Cutting-edge gravity flush models that approach low-flow pressure-assisted toilets in water savings. May require double flushing bulk waste.

Pressure-Assisted Toilets

Pressure-assisted toilets use compressed air to force a pressurized jet of water into the bowl when flushed. Typical GPF ranges:

1.0-1.6 GPF – First generation pressure-assisted models. Offer significant water savings over old 3.5+ GPF toilets.
0.8-1.0 GPF – Current high-efficiency pressure-assisted toilets rival ultra low-flow gravity models.

So in summary, the lowest GPF toilets today are generally pressure-assisted models under 1 GPF or gravity-flush models under 1.1 GPF. Choosing one of these high-efficiency toilets provides maximum water savings.

Choosing a Toilet Based on Gallons Per Flush

When shopping for a new toilet, the GPF should be one of your most important considerations, along with bowl shape, flushing power, size, and other factors. Here are some GPF-based tips for choosing the right toilet:

Look for the EPA WaterSense label. These models are independently certified not to exceed 1.28 GPF.
For maximum water savings, choose an ultra high-efficiency toilet under 1.1 GPF. Under 1 GPF is ideal.
If you need more flushing power for heavy waste, opt for a pressure-assisted toilet rather than a gravity-flush model.
Make sure the lower GPF will sufficiently clear waste in one flush. Read customer reviews for potential clogging issues.
Calculate the water savings over your old toilet. Multiply the GPF difference by daily flushes and 365 days per year.
Be aware that low-GPF toilets may require some adjustment in flushing habits and extra cleaning to prevent clogs.

Prioritizing a low gallons per flush toilet is a simple way to save significant amounts of water over time with no loss of flushing performance. And choosing an ultra high-efficiency model gives you peace of mind that your toilet is doing its job while conserving as much water as possible. Focus on this key specification when shopping and you can enjoy all the benefits of a green, water-saving toilet optimized for your household’s needs.

Frequently Asked Questions About Gallons Per Flush

What are the most common GPF ratings for toilets?

Most toilets today are rated at 1.6 GPF or lower. The standards have progressed from 3.5 GPF in the 1980s down to 1.28 GPF or less for most new models. Ultra high-efficiency toilets can be 0.8-1.1 GPF.

How much water can I save with a lower GPF toilet?

With a 1.6 GPF toilet instead of an old 3.5 GPF model, you can save about 12,300 gallons per year with 5 flushes per day. Choosing an ultra-efficient 1 GPF toilet saves an additional 2,500 gallons per year.

Do lower GPF toilets clog more easily?

In some cases yes, but many modern low-flow toilets are designed to prevent clogs just as well as higher GPF models. Pay attention to wide trapways, glazed flush passages, and siphon-jet designs for less clogging.

Should I get a pressure-assisted or gravity-flush low-GPF toilet?

Pressure-assisted models provide the most reliable flushing power, but some people dislike the loud flush noise. Quieter gravity-flush toilets work well for solid waste if the bowl shape and siphon action are designed properly.

How can I determine the GPF of my existing toilet?

If your existing toilet was manufactured post-1994, it is likely 1.6 GPF. For older models, check inside the tank for a flush valve rating or run a tank capacity test by measuring the fill volume.

Is a dual-flush toilet more water efficient than a standard low-GPF toilet?

Dual-flush toilets can save more water when accounting for liquid-only flushes using less water. However, the GPF for a full-flush on a dual toilet is often still 1.6 gallons or more. So single-flush toilets under 1.6 GPF generally use less water overall.

What percent of household water usage goes to toilets?

Toilets account for about 28% of total indoor water usage in a typical home. Showers and faucets lead at 35% and 33% respectively. So high-efficiency toilets are important, but comprehensive water conservation must address all usage areas.

Conclusion

I hope this detailed overview has helped explain what gallons per flush means and how GPF impacts your toilet selection. The key takeaways are:

Gallons per flush measures the total amount of water used per toilet flush.
Lower GPF indicates higher water efficiency and savings.
Modern toilets have reduced GPF from over 5 gallons to under 1.6 gallons or lower.
Choose an ultra high-efficiency toilet under 1.1 GPF for maximum water conservation.
Compare GPF ratings across toilet models to find the best combination of water savings and performance.

Let the GPF guide you toward the most suitable water-saving toilet. A low-flow high-efficiency toilet with proper dual-flush or gravity-flush siphoning action will serve your household’s needs while conserving water and saving money on utility bills. With the knowledge of gallons per flush ratings and standards, you can make an informed, environmentally responsible decision for your next toilet purchase.