What is the device used to measure the amount of water flowing from an open tap?

• A. Weir cup
• B. Flow meter
• C. Hydrometer
• D. Pitot tube

Answer: (A)

Measuring how much water comes out of an open tap is about discharge—the volume that passes per unit time. A weir cup is a simple, calibrated container used with a small notch weir to capture that discharge and make the flow measurable. Place the cup under the tap and run the water for a fixed period, then read the volume collected on the cup’s marks and convert that to a flow rate (for example, liters per minute) by dividing the volume by the time elapsed. This method is quick, inexpensive, and provides a tangible sense of what the faucet delivers, which is why it’s commonly used for basic flow checks in plumbing practice. In more precise or professional settings, a dedicated flow meter can give continuous readings, but the weir cup offers a practical way to estimate faucet discharge when simpler equipment is preferred.