To determine a Toilet's Flush Volume

There are three options you can take to determine your toilet's flush volume. The first method is the easiest and best. If you cannot find it that way, try the second and then the third, if necessary.

METHOD #1 TO DETERMINE A TOILET'S FLUSH VOLUME:

1. Look for marks or labels near the toilet seat hinge.
2. A 5-gallon per flush (gpf) toilet might be shown as 22.73 liters, a 3.5 gpf as 15.91 liters. All 1.6 gpf (6.1 liters) toilets should be marked at this location.
3. If no markings, check the underside of the tank lid or the tank’s back inside wall for a date stamped in the porcelain.
4. Toilets produced before 1985 are 5 to 7 gpf.
5. Toilets produced between1985 to 1991 would be 3.5 gpf.
6. All toilets manufactured after 1991 are 1.6 or less per flush.

METHOD #2 TO TEST TOILET FLUSH VOLUME IS BY MEASURING THE TANK

1. Measure the length of the tank.
2. Measure the width of the tank.
3. Measure the full water level in the toilet tank (depth 1).
4. Flush the toilet and measure the drop at the lowest level (depth 2).
5. Subtract depth 2 from depth 1. This will give you the “drop” measurement.
6. Multiply the length times the width times the “drop” to determine the volume of cubic inches of water used per flush.
7. Divide the volume by 231 to get the number of gallons per flush.

METHOD #3 TO DETERMINE THE TOILET FLUSH VOLUME IS BY READING THE WATER METER.

1. Read your water meter
2. Make sure all water-using fixtures are turned off (reading 1).
3. Flush the toilet and then read the meter again (reading 2).
4. Make note of where the sweep hand is for gallons up to 10.
5. Subtract reading 1 from reading 2 to determine the amount of water used in a flush.