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Determining & Recording Old Toilet's Gallons Per Flush
For verification of eligibility, and statistical and monitoring purposes, each applicant is required to provide the toilet’s volume of gallons per flush (gpf). Your old toilet’s gallons per flush must be recorded on the application.

The flush volume of a toilet simply means how much water is released when it is flushed. To qualify for this rebate program you must be replacing a toilet currently using 3 gallons per flush or more. So, that means you need to know your toilet’s flush volume.

Manufacture Date of Old Toilet

Equals This Many Liters Per Flush

Gallons Per Flush

Pre-1950's to 1980

18.92 to 26.49

5 to 7




1994 to present

6.05 (does not qualify)             


1994 to present

4.84 (does not qualify) 


Here are two ways to determine your old toilet’s Gallons Per Flush:

1) A marking or label is typically located near the toilet seat hinge on the bowl that can provide you with that information. Please note that the markings and labels are often in liters as opposed to gallons. Look above for a quick reference to help determine your toilet’s flush volume if it is listed in liters or has the manufacturing date labeled.

If you cannot locate any markings or labels near the seat hinge, check the underside of the tank lid or the tank’s back inside wall for a date and information stamped in the porcelain.

2) If you have access to the Internet, go to ‘How to Measure Toilet Flush Volume’ by Green Team Real Estate to view a quick video instruction for measuring your toilet’s gallons per flush.

Then proceed with the following activity. You will need: Pencil & 1-gallon empty milk jug

  • Turn off the water supply behind the toilet by turning the valve to the right. Remove the tank lid from the toilet and set aside. If you have a water saving device inserted in your toilet tank, please remove before conducting this activity.
  • Mark the water level inside both the toilet tank and toilet bowl with a pencil line.
  • Flush the toilet until it doesn't fill up with water any more.
  • Measure TANK gallons: Fill a 1-gallon empty milk jug with water, and pour the water into the tank until you reach the pencil line. Refill the container as needed, and keep track of how much many jugs (or portions of jugs) of water it took to fill the tank to the pencil line.
  • Measure BOWL gallons: Fill the toilet bowl until the water reaches the pencil line, and keep track of how many jugs (or portions of jugs) of water it took to fill the bowl.
  • Add together the number of jugs and portions of jugs (this is your gallon equivalent: 1 jug = 1 gallon) it took to fill the tank and the bowl together to determine your toilet’s gallons per flush rate.
  • Replace the water tank lid, and turn the water supply on by twisting the valve to the left.
  • Record your old toilet’s gallons per flush rate on the application form

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