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On average, a person flushes a toilet 5 times a day, with each consuming 1.2-5 gallons of water. So to know about “how much water is used to flush a toilet?” make sure to read this guide to the end.

All toilets have the same appearance to the naked eye, but there is a whole different story inside. Every toilet is separate from another due to its functions such as size, shape, height, flushing system, and water consumption.

The water consumption of conventional toilets is higher at 5-7 gallons per flush. But the more modern low-flow toilets utilize 1.28-1.6 gallons per flush, making them more efficient. This makes your toilet the largest water-consuming household item.

Let’s find out more about “how much water is used to flush a toilet?”.

High Water Consumption Toilets

From the ’80s and early ’90s, the older toilet models were considered high water-consuming toilets. The older models can use 5-7 gallons of water per flush, with some even higher than 8 gallons.

If you happen to have an old toilet in your bathroom and it is flushed 5 times a day on average, you are flushing 25-35 gallons of water. This rate of water consumption, in the long run, can cost you a lot on water bills.

Despite humongous water use, the older toilets flush the bowl thoroughly. Older toilets have a gravity flushing system by which large amounts of water are introduced through the bowl to flush it thoroughly.

By looking at these numbers, we can see that older toilets are uneconomical when it comes to water consumption. And according to the modern standard, these types of toilets are obsolete.

Low Water Consuming Toilets

After careful considerations, the manufacturers started producing low water consumption toilets from the mid-’90s. The new improvements in the toilet design resulted in low water consumption of 1.6 gallons per flush.

At first, people were not used to the idea of low water-consuming toilets and complained about decreased efficiency. But gradually, with more improvements, the low water consuming toilets became as efficient as older models without wasting too much water.

As mentioned above, the toilet is the largest water-consuming unit in any house. So the low water consuming toilets save lots of water and slash water bills in half.

High-Efficiency Toilets

Modern toilets can also be categorized as high-efficiency toilets or HET. These toilets utilize 1-1.28 gallons of water per flush. This way, these toilets save more than 9000-12000 gallons of water annually.

The high-efficiency toilets are available with gravity-assisted flushing, priced lower than pressure-assisted toilets. While pressure-assisted toilets are priced higher, they tend to be more efficient. They have another pressurized tank inside the main water tank and release a water-air pressurized mix to flush the toilet.

For better operation, the modern toilets have other features incorporated. The bowl and trap way are glazed for easier cleaning; the bowl is designed for efficient flushing, large siphon jets for instant flushing, and self-cleaning surface coatings. These features combine to reduce the water consumption to 1-1.38 gallons per flush.

EPA WaterSense Certification

The Environmental Protection Agency of the United States has sponsored a program known as WaterSense in 2006. It was initiated to increase water efficiency and conserve water. Every toilet that utilizes 1.28 gallons per flush is WaterSense certified in the US.

The newer guidelines specify the water consumption rate of not exceeding 1.28 gallons per flush. This applies to every type of water tank and flushing system. It results in water saving up to 13000 gallons and 140$ in savings annually.

Types of Flushing System

Like many, toilet models either operate by using gravity or pressure-assisted flushing. Furthermore, the toilets also come in as single and dual flushing options. According to the new specifications of EPA WaterSense certification, all types of flushing systems should use 1.28 gallons per flush.

Gravity Flushing Toilets

The gravity flushing toilets are the most common and most straightforward type. Although this type of flushing system used 5-8 gallons of water in the past now, modern gravity flushing toilets use 1.28-1.6 gallons of water.

Advancements such as glazed bowls and trap ways create a smooth surface for water to glide and clean efficiently. The larger flush valves and siphon jet action bowls have also made flushing quicker and cleaner with less water.

Pressure Assisted Toilets

Pressure assisted flushing system is a modern invention. It functions by a pressurized tank inside the water tank. It requires 25Psi of pressure for this system to work correctly. A modern flushing system only requires 1-1.28 gallons of water per flush.

These toilets are true high-efficiency, low consumption toilets and save up to 13000 gallons of water annually. The pressure-assisted toilets are efficient but louder than the gravity-fed systems.

Single Flush Toilet

Single flush toilets tend to be more water-consuming because it requires flushing solid and liquid waste with the same amount of water. The single flush toilets are available in gravity and pressure-assisted systems. The water consumption of single flush toilets is 1.28-1.6 gallons.

Dual Flushing Toilets

The dual flush system is available in more modern toilets. This type of toilet can be used for half and full flush according to the needs. The half flush is utilized for liquid waste removal and consumes 0.8-1 gallon of water. While the full flush is used for solid waste removal and consumes 1.28-1.6 gallons per flush.

Is your toilet consuming more water?

The most common issue of excess water consumption by a toilet is a leakage in the system. When the flush valve or flapper becomes loose, it constantly leaks water inside the bowl. Not only does this causes water waste, but it also affects the flushing performance.

On average, a minor toilet leak can result in the wastage of 30 gallons of water per day. While a medium leak causes wastage of 200 gallons per day. However, a significant leak can result in over 4000 gallons of water wastage and additional damage to the property.

Another reason for excess water consumption is that your toilet is an older model. Older models can consume 5-7 gallons of water per flush. If you are frustrated due to this problem, it is time to switch to a newer model.

Often, excessive water consumption occurs when the water tank and bowl fill at different rates. After a flush, the bowl and water tank starts to fill up to their mark. But if one fills faster than the other, almost a gallon of water can be wasted. Luckily this issue can be fixed by your plumber.

If everything seems to be working fine and the toilet is still consuming more water, you should check the flush handle. Sometimes the flush handle gets stuck, and water keeps dripping down the drain.

How to Save Water Consumption of a Toilet?

Although modern toilets are known for low water consumption, there are specific ways you can save a lot of water. The following tips can also work for older toilet models.

  • Instead of throwing toilet paper inside the toilet, you should always use the bin to reduce stress on the flushing system and save water.
  • Adjust the water intake inside your toilet by adding an adjustable flapper valve.
  • Go for the dual flushing toilet and save more water.
  • Check for leaks and repair or replace faulty toilet parts.
  • Install a tank bag to reduce the amount of water in the tank.
  • Install a fill cycle diverter to eliminate water wastage when the bowl and tank don’t fill equally.

Some Water-Efficient Toilet Models

The leading manufacturers of modern water-saving toilets are American Standard, TOTO, and Kohler. Their toilets are well known for their high-quality build and low water consumption. Here are some of the most water-saving toilets that you can buy.

Toto Eco Ultramax is a single-piece toilet with two models, the E-Max, a 1.28 GPF toilet, and G-Max, a 1.6 GPF model.

Kohler Elliston is a two-piece toilet with a comfortable height and water consumption of 1.28 GPF.

Kohler Cimmaron is a 1.6 GPF-consuming toilet and features Aquapiston technology. Some of the Cimarron models are available with a 1.28 GPF option.

American Standard Vormax is a water-saving toilet consuming only 1.28GPF water with its signature Vormax technology.

American Standard Cadet 3 is another water-saving toilet with many variants. The most common of which is the 1.28GPF model.


So after carefully discussing all the details, we can conclude that a person flushes a toilet 5 times a day on average. If the toilet is of the older model, expect a 5-8 gallons water consumption. While the newer high-efficiency toilets consume water at the rate of 1-1.6 GPF. So the modern toilets not only save water but also cut your water bills in half.

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