To see how much water your toilet uses, look for a date or number stamped in the porcelain. Look under the tank lid, on the tank wall or near the seat hinge. The date is the year it was manufactured; if followed by L, use the liter conversion to determine the gallons used per flush.
Based on the year, the toilet flow rate is:
Before 1980: 5 to 7 gpf
1980-1994: 3.5 gpf
After 1994: 1.6 gpf *Note-Does not qualify for this program.