Basic Principles of a Water Meter

A water meter is a device that measures the amount of water being used by a consumer. Most developed countries use water meters to measure the volume of water used by a commercial or residential building. They can also be used at a well, water source or water system to determine the flow of water via a specific portion of the system.

Several types of water meters are currently being used. However, the choice depends on the accuracy requirements, the required flow rates, the end-user, and the flow measurement method.

Types of Water Meters

The water meters are classified into two basic types as follows:

Positive Displacement Meters

With this type of meter, a known quantity of liquid within a small unit moves with the flow of water. They operate by repeatedly filling and emptying the unit. The flow rate of water is calculated based on the number of times the unit is filled and emptied. The meter also includes a piston or disc that triggers the motion of gears for recording the volume of liquid exiting the meter.

These meters exhibit high accuracy over a wide range of flow rates, and they are sensitive to low flow rates.

Velocity Meters

Velocity meters measure the velocity of the water flow and convert it into the amount of water flow. They operate based on the principle that water passing through a known cross-sectional area having a measured velocity is proportional to the volume of water flow.

This type of system employs different mechanisms to measure the velocity, which include multi-jet meters, propeller meters, magnetic meters, ultrasonic meters, orifice meters, venturi meters and turbine meters.

Most of the velocity-based meters have an adjustment vane for calibrating the meter to the required accuracy. Teledyne, an expert in the manufacturing of process control and precision measurement instruments has released the LaserFlow sensor design to measure water in open channels:

LaserFlow™ Non-contacting Area Velocity Sensor

Water Meter Reading

A standard water meter uses two common types of registers - straight and circular - to read the flow of water in cubic feet or inches.

The registers can be observed on the surface of the meter. The straight registers can be read like an odometer in a car. On some larger meters, a multiplier will be present on the register face, which can be noted as 10X, 100X, or 1000X based on the size of the meter. Circular registers, on the other hand, are more complex to calculate water usage. They employ a series of dials marked with divisions of ten.

There are several ways of reading the water meter, which includes:

  • Direct reading
  • Remote reading, which is accomplished via an electronic signal using a wire where one can either directly read or touch read.
  • Touch read or plug-in reading that employs a handheld device that acquires the electronic signal by touching the remote station or plugging-in. The signal is then translated into the readings that are stored in the handheld device.
  • Automatic meter reading, in which the meter reader obtains readings through radio transmission.


Given below are some of the major uses of water meter:

  • It detects water leaks in the distribution network
  • It identifies potential well, pump, or irrigation system problems
  • It determines the efficiency of a water plant for supplying water.

Sources and Further Reading

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  1. Bhargavi bharu Bhargavi bharu India says:

    The water consumption trends and reports help you better understand your consumption and bring changes for better utilization of water.mablei water meters measure water using ultrasonic sensors, so there is no wear and tear as in mechanical meters. The smart electronic circuits take the meter readings and upload the data without manual intervention

The opinions expressed here are the views of the writer and do not necessarily reflect the views and opinions of

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