Flow rates for showers are expressed on the water rating label in litres per minute (L/min).
The most water efficient showerheads have a 4 star WELS rating demonstrating a flow rate of 6 litres per minute or less.
The star rating takes into consideration overall performance of the shower in addition to its water consumption.
Showers are tested for:
• angle at which water sprays from the head (to be between 0°and 8°)
• drop in temperature between 150 mm and 750 mm below the shower head (no more than 3°C)
• endurance of the flow controller by being turned on and off around 50,000 times
• spray force and coverage (4 star showers only)
• water consumption
Every 1L/min difference will save a typical family of four nearly 12,000 litres (12kL) of water and $35 each year.
For this family of four, replacing their shower that flows at 15L/min with a new:
• 3-star shower that flows at 9L/min will save 70kL and $210 each year on their water bills
• 4-star shower that flows at 6L/min will save 105kL and $315 per year on their water bills.
Depending on energy costs, they may save an equivalent amount (or more) each year on energy bills because less water will be heated for showers.
Assumptions: each family member showers for 8 minutes 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).