Water meter is a device that measures the volume of water that flows through a pipe or a large channel. The most widely known type of water meter turns numbers on a register that operates like an odometer (mileage recorder) of an automobile. This type is used by water companies to measure the water used in homes, factories, and business establishments.
In mild climates, such a home water meter is installed in a small box outside a house on the service line (pipe) leading to the street. In cold climates, the meter is installed inside a house–usually in the basement–to protect it from freeze-ups during winter. The meter is often connected to a register mounted outside the house so that the meter reader does not have to go inside.
The measuring chamber of a residential-type water meter usually contains a disk. Incoming water causes the disk to wobble. The amount of water that flows through the chamber determines how much the disk moves. The motion of the disk turns the numbers on the register. A large number of water meters use a magnetic coupling to transfer the disk’s motion to the register. The register records the flow of water in cubic feet, gallons, or liters.
Other types of meters continuously register the flow of water on a chart-recording instrument. These meters are used in filtration plants, pumping stations, and industries.
The venturi meter and the orifice meter restrict the passage through which the water moves. They are used to measure the difference in water pressure to determine the amount of the flow.
The magnetic flow meter uses two electrodes mounted flush in the walls of a pipe, outside of which have been mounted powerful magnets. Ions (electrically charged atoms or groups of atoms) carried in the water pass through the magnetic field and generate voltage used by the meter to measure the water flow.
Electronic meters measure water flow by measuring changes in the wavelength of the sounds made by moving water. A variety of other devices are used to measure the flow of water in open channels, such as sewers and rivers.
