Metering of water supply is usually motivated by one or several of four objectives: First, it provides an incentive to conserve water which protects water resources (environmental objective). Second, it can postpone costly system expansion and saves energy and chemical costs (economic objective). Third, it allows a utility to better locate distribution losses (technical objective). Fourth, it allows to charge for water based on use, which is perceived by many as the fairest way to allocate the costs of water supply to users. Metering is considered good practice in water supply and is widespread in developed countries, except for the United Kingdom. In developing countries it is estimated that half of all urban water supply systems are metered and the tendency is increasing. Water meters are read by one of several methods: the water customer writes down the meter reading and mails in a postcard with this info to the water department; the water customer writes down the meter reading and uses a phone dial-in system to transfer this info to the water department; the water customer logs in to the website of the water supply company, enters the address, meter ID and meter readings [6] a meter reader comes to the premise and enters the meter reading into a handheld computer; the meter reading is echoed on a display unit mounted to the outside of the premise, where a meter reader records them; a small radio is hooked up to the meter to automatically transmit readings to corresponding receivers in handheld computers, utility vehicles or distributed collectors a small computer is hooked up to the meter that can either dial out or receive automated phone calls that give the reading to a central compute

system. Most cities are increasingly installing Automatic Meter Reading (AMR) systems to prevent fraud, to lower ever-increasing labor and liability costs and to improve customer service and satisfaction. Water metering is common for residential and commercial drinking water supply in many countries, as well as for industrial self-supply with water. However, it is less common in irrigated agriculture, which is the major water user worldwide. Water metering is also uncommon for piped drinking water supply in rural areas and small towns, although there are examples of successful metering in rural areas in developing countries, such as in El Salvador.[1] Metering of water supplied by utilities to residential, commercial and industrial users is common in most developed countries, except for the United Kingdom where only about 30% of users are metered.[2] In some developing countries metering is very high, such as in Chile where it stands at 96%, while in others it still remains low, such as in Argentina. A water meter is a device used to measure the volume of water usage. In many developed countries water meters are used to measure the volume of water used by residential and commercial building that are supplied with water by a public water supply system. Water meters can also be used at the water source, well, or throughout a water system to determine flow through that portion of the system. In most of the world water meters measure flow in Cubic metres (m3) or litres [1] but in the USA and some other countries water meters are calibrated in cubic feet (ft.3), or US gallons on a mechanical or electronic register. Some electronic meter registers can display rate-of-flow in addition to total usage.