Calculate shower flow from the water collected and the time taken. Enter the measured volume and seconds to view litres per minute, US gallons per minute and Imperial gallons per minute, then keep the result with your shower configuration.
Collecting 3 litres in 20 seconds gives 9 litres per minute. At a constant 9 litres per minute, an 8-minute shower uses an estimated 72 litres. These figures illustrate the calculation; they are not a performance rating for a QSW product.
Use the water actually collected during the timed measurement. Keep the shower setting unchanged and capture the full outlet flow. The result describes that measurement condition; it is not a pressure reading or a certification test.
Flow rate is the collected volume divided by the collection time. To calculate litres per minute, divide the measured litres by the number of seconds and multiply by 60.
Flow in L/min = collected litres ÷ elapsed seconds × 60
For example, collecting 3 litres in 20 seconds gives a flow of 9 litres per minute. This is a worked calculation, not the performance specification of a product in our catalogue.
Use a safe water temperature and keep the collection area clear. Do not infer water pressure from the bucket-test result. Pressure needs its own measurement, and the installed pipework, controls and outlet all affect the operating conditions.
If you enter a shower duration, the calculator multiplies the measured flow by that time. The estimate assumes the measured flow continues throughout the entered duration. Changes in controls, supply or outlet operation can change actual use.
Water used in litres = flow in L/min × duration in minutes
At 9 L/min, an 8-minute duration gives 72 litres. Both values are calculation inputs and do not describe a guaranteed product result.
Record the model, selected outlet, spray setting and measurement conditions with the result. If you are comparing shower products, use comparable conditions and identify whether the head was tested alone or as part of a full assembly.
Browse the relevant hand showers, fixed overhead heads or complete shower sets, then include your performance requirements in the enquiry. A flow result does not establish that another head will achieve the same result on a different installation.
No. The calculation describes collected volume over time. Pressure and certified performance require their own applicable measurements or documentation.
No. A US gallon and an Imperial gallon have different volumes. This calculator labels both results explicitly so they can be compared without mixing the units.
No. The calculation measures volume per unit of time. Record pressure separately using an appropriate measurement method and use the selected product's operating information.
Do not assume that simultaneous outlets deliver the same flow as one outlet running alone. Measure the operating arrangement you intend to assess.
PNNL Water Flow Rate explains volume, collection time and measured flow. It does not certify or recommend a QSW product.
Prepare a Shower Enquiry