The most water efficient dishwashers have a 6 star WELS rating.
Dishwashers are tested for:
• average total water consumption
• wash of a soiled load (equal to the maximum number of place settings the machine can carry)
• washing and drying effectiveness.
The water rating label will tell you how much water is used per load, and what cycle was used for the tests (‘normal’, ‘eco’).
For a family that runs one load of dishes per day, reducing water use by 10L per wash will save 3.7kL and $11 each year.
For a dishwasher that holds 14 place settings, choosing a 6-star machine that uses 9.5L per wash instead of a 2-star machine using 19L per wash will save this family 3.5kL and $20 each year.
Assumptions: figures are based on average water price of $2.99/kL (the national average price reported in the 2014–15 Australian Bureau of Statistics Water Account).