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What is GPF and why it’s important to your wallet

We all want a toilet that is low in cost. Did you know that a high GPF can unnecessarily drive up your water bill?

GPF in toilets means gallons per flush. Outside of the US GPF is also called LPF which stands for liters per flush. GPF and LPF are important because this number shows you how much water is used each time you flush. The less GPF the better for your wallet. But the lesser GPF isn’t always ideal.

Keep reading to find out the perfect GPF that’s recommended and why.

What does GPF mean?

GPF means how much water, measured in gallons, is used each time you flush your toilet. In the US most toilets have a 1.6 GPF meaning each time you flush you use 1.6 gallons of water. Toilets build before 1994 have a much higher GPF than toilets newer than that.

Out of all the water a household uses, about 30% is used by your toilet. This comes down to 7,000 gallons a year, per person. Needless to say that if you can save on toilet water you better do it.

What is the highest GPF for toilets?

The highest GPF for toilets is around 6 GPF. Toilets installed in homes way before 1994 often had a GPF of 6 or even higher. Compared to today’s standard that’s incredibly high. Toilets made after 1994 have to have a maximum of only 1.6 GPF.

It’s decided in the US that toilets should have a standard of 1.6 GPF because it’s way better for the environment to use as less water as possible.

What is the lowest GPF for toilets?

The lowest amount of GPF for toilets is 1.1 GPF. However, this is only possible when you have a toilet that has a dual flush: A button for liquids which has a 1.1 GPF, and a button for solids which has a 1.6 GPF. The lowest amount of GPF for single flush toilets has a GPF of 1.28.

Toilets bought and installed after 2016 often have a GPF of just 1.28. These new toilets have a WaterSense Certification which tells you they use very little water to flush.

However, the standard lowest GPF in most US homes remains 1.6 gallons per flush as single flush toilets are more popular, toilets last for decades, and most people have yet to update theirs to newer models.

What is the WaterSense Certification?

The WaterSense Certification is a certification given to toilets that use at least 20 percent less water than the standard 1.6 GPF. These toilets only have a GPF of 1.28. Toilets that have the WaterSense Certification, therefore, are very cost-effective which is great for your water bill.

Toilets with the WaterSense Certification perform equally or even superior to toilets with a higher GPF according to EPA.GOV.

Keeping a look out for toilets with this certification is something we advise buyers. Look for the following logo:

What is the best GPF for a toilet?

So how do you know how many gallons per flush is best? It depends on if your toilet is single flush or dual flush. By today’s standards:

The best GPF for a toilet is 1.28 for single flush and 1.1/1.6 for dual flush. A single flush toilet needs enough water to flush away solids each time the toilet is flushed. A dual flush toilet has the option to only use 1.1 GPF for liquids and 1.6 GPF for solids which makes the toilet’s water use optimal and cost-effective.

The lower the GPF the better for the environment and your wallet. So, the ideal GPF mainly comes down to what you need to flush away (but never more than 1.6 GPF!)

How to know what your toilet’s GPF is?

To know how much water your toilet uses each time you flush, you must look for a stamp that gives you information about the gallons per flush.

There are 3 ways to find out your toilet’s GPF (gallons per flush):

  • Between the toilet seat and water tank
  • Underneath the tank lid
  • Inside the tank on the walls
  • Google your specific toilet

If your toilet is old then you can be sure that your GPF is higher than the recommended 1.6 GPF. It’s probably between 1.6 and up to 4 GPF because the agreement to have toilets use less water was only made in ’94.

But did you know that you can minimize the amount of water you use per flush without buying a whole new toilet?

How to make your toilet use less water

There are a few ways you can modify your toilet to use less water.

You can:

  • Install a water-saving adjustable flapper
    • This way you can set the amount of water to be released from the tank by moving the float up or down
  • Use a water-saving bag
    • This biodegradable bag swells in contact with water which makes the tank use less water
    • Can save up to 0,32 gallons per flush (1.2 liters per flush)
  • Install a fill-cycle diverter
    • This diverts extra water from the bowl into the tank instead of the drain

Always thoroughly read the directions of each modifier before installing them onto your toilet. For very old toilets it’s sometimes better to replace your toilet altogether.

Is dual flush more cost-effective than single flush?

Dual flush is when your toilet has two buttons: one for urine and one for feces. A single flush toilet is a toilet that only has one button or lever.

Dual flush toilets are more cost-effective than single flush toilets. Liquids like urine don’t need as much force to be flushed away as solids, like feces. With dual flush toilets you can choose how much water (force) you need for your waste to be washed away. Single flush toilets always need enough force to flush away solids.

This means every time you flush with a single flush toilet you always flush as if you were to flush away solids. Since more water means more money, single flush toilets are more expensive than dual flush toilets.

And let’s be honest, we pee more than we poop. It would be wiser to purchase a dual flush. However, dual flush toilets tend to be more expensive.

Most frequently asked questions about a toilet’s GPF

Here are some of the most asked questions regarding a toilet’s GPF.

What should the GPF for a toilet be?

The best GPF for a toilet should be 1.28 for single flush and 1.1/1.6 for dual flush.

What is GPF and LPF in toilets?

GPF stands for gallons per flush and LPF stands for liters per flush. GPF and LPF are measurements that let you know how much water you use each time that you flush.

What does 3.5 gpf mean?

A GPF of 3.5 means that this toilet uses 3.5 gallons of water per flush. By today’s standards, this is very high.

What does 1.28 gpf mean on a toilet?

A GPF of 1.28 means that this toilet uses 1.28 gallons of water per flush. By today’s standards, this is normal for single flush toilets.

Is dual flush better than single flush?

Dual flush is better than single flush because it’s more cost-effective due to the choice of GPF. This way you can use a smaller amount of GPF for liquids and a higher amount of GPF for solids.

What to do when you have GPF problems

Identify your problem and ask for help from a local plumbing service. If you want to improve your GPF you can buy special bags to minimize the amount of water used per flush, or you can update your toilet.

Disclaimer: is not responsible for any damage caused to your toilet by (wrongly) interpreting information found on this site. Please seek custom advice from a professional to evaluate your current situation.