0.8 refers to a 20% reduction in flow rate to allow for pressure loss in your system. If the bucket test is taken off the main water feed at the correct pressure then this 20% allowance is not necessary.
Note the time of day you plan to run your irrigation. Water pressure and flow can fluctuate throughout the day, so it is best to time the flow at the same time of day.
Ensure there is no water running elsewhere on your property.
Turn on the tap fully without the bucket underneath.*
Place the bucket under the already running water, and time how long it takes to fill
Use our handy Bucket Test Flow Rate Calculator to find out the flow rate in L/min (Litres per minute). Note that this calculator already includes the 20% reduction in flow rate as listed above.
Note that the fill time needs to be calculated at full flow and mid-stream, so the bucket must be placed under the tap after it is already running.