What is GPF Toilet? (Fully Explained)

Written by

Paulk Webb


Freddie J. Hagopian

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what is gpf toilet

Nowadays, all the toilets have that GPF rating as part of their marketing label. Do you even know, “What is GPF toilet?”

Also known elaborately as gallons per flush, the GPF toilet meaning tells you how many gallons of water to flush a toilet in general. On average, this figure ranges from 1.1 to 8 gallons, with older units consuming more water.

Continue reading to learn more about toilet GPF’s meaning and effects on the functions of the commodes.


How Does GPF In Toilets Affect Flushing?

The GPF metric is a significant indicator of a toilet’s water consumption and flushing performance. You’ll want a low GPF without compromising the flushing power.

1. Water Consumption


The toilet flush rate indicates how much water the commode requires with each flush:

  • For example, older units manufactured before 1982 have the highest GPF toilet of 5-8, so a minimum of 5–8 gallons of water is necessary for flushing the bowl.
  • Toilets manufactured before 1992 use 3.6 GPF, meaning they consume 3.6 gallons each flush.
  • Models produced recently have a lower toilet flow rate of 1.1. So, the commode will only require 1.1 gallons of water to wash away the waste in the bowl.

As you can imagine, a higher GPF will result in higher water bills, so it’d make sense to go for the lowest GPF toilet possible to save more money.

  • Toilets with a GPF rating of 1.6 should be able to save $50-$100 in water bills per year.
  • New flushing technologies patented in 2014 even cut down the GPF rating to 1.1-1.28. These water-efficient toilets are the fad nowadays because they not only use less water but also maintain a strong flushing performance. By using these toilets, your family can save $140 or more in water bills a year.

2. Performance

One main concern over low GPF toilets is that poor flushing power could result in clogs, as evidenced by the low-flow units in the 1990s.

However, newer models, particularly the ones with WaterSense labels, boast a great balance of high flushing performance and low water consumption. Equipped with either pressure-assisted or gravity-fed flushers, these commode types can ensure the waste passes through the pipe without leaving any trace on the bowl.

Ideal GPF Rating


Currently, the national toilet standard is 1.6 GPF or lower to save water resources, but many states, such as California, Texas, Colorado, and Nevada, have lowered the standard to 1.28 GPF. There’s a slight difference in water volume, but the latter provides more savings on your water bills. 

The 1.6 GPF toilets provide more flushing power than their 1.26 GPF counterparts. The higher toilet tank capacity and larger flush valves ensure that the waste passes through the pipes with fewer clogs. However, more power means more noise which can be a turnoff for those who want a silent operation.

If you want to reduce your water bills further, the 1.26 GPF toilets are ideal. However, you should look for models with WaterSense labels to ensure that their flushing performance does not suffer from the low GPF.

Read more: 1.28 vs. 1.6 GPF toilets: What’s the difference?

How to Check Toilet Flush Volume on Your Toilet


The easiest way to determine how much water your toilet uses per flush is to look for the GPF rating label, which is often stamped or printed 0n the toilet seat, tank, and lid.

If you can’t find the GPF rating label, look for the manufacturing date. The date stamp is often located on the base of the tank lid or behind the tank. Here’s a chart showing the different flush volumes for a certain period.

Manufacturing Date Gallons Per Flush (GPF)
Pre-1982 5-7
1982-1992 3.5
1993-present 1.6
2004-present 1.28
2014- present 0.8-1.1

If you still can’t find the manufacturing date, you’ll need to do some math. First, you’ll need to turn off the water shut-off valve and do these steps.

  1. Take the tank lid off. Then, use a pen to mark the water level in the tank and the bowl.
  2. Flush the toilet to remove the water in the tank. Since the water supply is closed, the tank won’t be refilled.
  3. Get a 1-gallon container and fill it with water. Pour the water inside the tank and count how many times it takes to reach the marked spot.
  4. Next, pour water into the bowl and count how many times it takes to reach the level mark.
  5. For example, you get one gallon for the tank and slightly more than half a gallon for the bowl. Add them together to get the flush volume, which is 1 + 0.6 = 1.6 GPF.


Now that everything is clear about “What is GPF toilet?”, you can shop for a new toilet with more knowledge. You can choose the standard 1.6 GPF, but even save more water with water-efficient 1.28 GPF models. The key is to find the right balance between performance and low water consumption.

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