Execution of the measurement
Ensure an accurate measurement by running the pump or water source under normal conditions. Remove any nozzles, spray guns, or filters at the end of the hose so that the water can flow freely. For a dry-installed pump or hydrophore pump, the pump housing must be completely filled with water to prevent suction problems.
Follow these steps for the test:
- Take a bucket or container of which you know the exact volume (for example, 10 liters).
- Hold the hose at the height where the water should eventually come (for example, the top of a waterfall in a pond).
- Place the bucket under the stream and start your stopwatch immediately.
- Stop the time as soon as the bucket is filled exactly to the edge.
Repeat this measurement three times and calculate the average number of seconds. This minimizes measurement errors due to reaction time and fluctuations in water pressure.
Calculation and results
With the average duration, you calculate the actual capacity. The outcome gives the flow rate in liters per hour (L/h). Use the following formula for this:
Capacity (L/h) = (Volume of bucket in liters / Time in seconds) × 3600
Suppose you fill a bucket of 10 liters in an average of 20 seconds. The calculation is then: (10 divided by 20) times 3600. The net capacity in this case is 1,800 liters per hour.
Do you measure a value that is lower than the specifications of the pump? This is because this is the gross capacity, the net capacity depends on the following:
- Head: every meter that water has to be pumped up significantly reduces the flow rate.
- Hose resistance: long hoses, narrow diameters, and ribbed inner sides inhibit the flow.
- Couplings: bends and fittings cause extra friction.
Use this net capacity to check whether your pump is powerful enough for your filter installation or the planned number of sprinklers in your irrigation zone.
Also use our handy bucket test tool below for easily calculating your capacity.
