Which of the following is NOT a common type of water meter?

The choice of "Infrared meter" as the answer is appropriate because it is not a common type of water meter used for measuring water flow in distribution systems.

Positive displacement meters are widely utilized in residential and commercial applications. They work by having water fill a measurable chamber, allowing for accurate measurement of the volume of water that has passed through.

Velocity meters are also prevalent in water distribution. These meters measure the velocity of water flowing through a pipe, typically using methods such as turbine or ultrasonic sensing, and then calculate the flow rate based on that velocity.

Magnetic meters are designed to work on the principle of electromagnetic flow measurement, suitable for various applications and capable of measuring conductive fluids without any moving parts.

In contrast, while infrared technologies are used in some measurement applications, they have not been adopted as a standard method for measuring water flow in meters. Thus, identifying infrared as the meter type not commonly used highlights the distinctive roles and applications of the other common meter types in water distribution.