The water consumption of push and automatic shut-off taps can be calculated for input into the Wat 01 calculator using the following steps:
Step 1: Calculate the water consumption per person per use.
If a tap runs for less than 20 seconds per activation, assume it will be activated twice per person for the timed duration. For example, for a tap with a flow rate of 9 litres/min and a 15 second usage duration, the water consumed per person would be: 9 x 15/60 x 2 = 4.5 litres/min.
If a tap runs for 20 seconds or more per activation, assume one activation per person for the timed duration. For example, for a tap with a flow rate of 9 litres/min and a 20 second usage duration, the water consumed per person would be: 9 x 20/60 x 1 = 3 litres/min.
Step 2: Multiply the water consumption figure per person by 1.5 and enter this figure into the calculator tool.
Multiplying by 1.5 adjusts the consumption figure to compensate for the typical non times tap use of 40 seconds that has already been taken into account in the tool. Taking the first example above, if we multiply 4.5 litres/min by 1.5 we get 6.75 litres/min. When this is used in the tool as the flow rate specification, the consumption is 4.57 litres/person/day which more closely reflects the true level of water consumption for the push tap.