Can ShowerStar sense water flow rate?

No, ShowerStar is unable to sense water flow rate. ShowerStar uses non invasive vibration sensing to sense water flow and does not come into direct contact with water to enable it to sense water flow rate.

ShowerStar is however able to give you an approximation of flow rate and water used. Use the flow rate measurement bag (supplied with your SHowerStar) to measure the typical flow rate of your shower. 

ShowerStar then uses the typical flow rate eg 9 litres per minute multiplied by the time the shower has been running eg 5 minutes to calculate water use. In this examples 9 litres x 5 minutes = 45 litres.