Flow rates for toilets are expressed on the water rating label in litres per average flush, litres per full flush, and litres per half flush.
The most water efficient toilets have at least a 4 star WELS rating.
Toilets are tested for:
• endurance of inlet and outlet cistern valves
• performance in discharging material at full and reduced flush
• physical distortion
• water consumption
For toilets, the water rating label will tell you how much water is used in an average flush.
Every litre less water that a toilet uses in an average flush, will save a typical family of four nearly 6kL and $17.50 each year in water supply charges.
If this family replaces an old single-flush toilet with a flush volume of 12L with a new 4-star toilet with an average flush volume of 3.5L, this will save 50kL and $148 each year on their water bills.
Assumptions: each family member flushes 4 times per day, at an average water price of $2.99/kL (the national average price reported in the 2014–15 Australian Bureau of Statistics Water Account).