In the recent past, the demand for freshwater throughout the world has increased mainly due to the world’s growing population, and due to changing lifestyles which contributed to higher water consumption. The increase is more pronounced in urban areas, which normally have higher population densities, in addition to production industries, that typically consume large amounts of water. In general, the supply of freshwater to urban areas, for domestic and industrial use has become more challenging.
Water Conservation in urban areas has taken an integrated management approach. Variety of methods and techniques have been adopted worldwide, to conserve water, as a response to the problem of scarcity of freshwater. It includes, use of less water while avoiding wastages, use of flow restricting taps and showers, optimisation of toilet and urinal flushing, use of water efficient appliances and technologies, rainwater harvesting and effective reuse, automatic leak detection etc. Perhaps, the most effective strategy that is widely used for urban water management is water metering.
A water meter is a device for measuring and registering the amount of water that passes through a pipe or other outlet, usually for billing purposes. Water meters are also called as volume counter, flow-gauging device, water totalizator, flowmeter, or accumulator etc.
The purpose of a water meter is, to measure the amount of water (usually on a volumetric basis such as litres, mega litres or cum) supplied to a consumer over a specified period, for billing purposes. It ensures equity in water usage charges and better demand management.
Objectives of household metering
Water conservation- Compel people to consume less water through volumetric charges.
Revenue generation and provision for future investment.
Individual household equity- Avoid discriminatory practices associated with fixed rate tariffs and charging according to the usage volume.
Leakage detection and management through information on water consumption.
Reduction in peak demands.
Social equity, by favoring poor consumers who use less water, with lower tariffs or through subsidies.
Operation and planning of the water system can be improved, using data related to demand and supply.
Types of Water Meters
Water meters can be classified according to the technology used for their functioning.
Mechanical meters: Mechanical meters are positive displacement flow meters. Two common types of mechanical meter are, oscillating piston meters and nutating disk meters. Either method relies on the water to physically displace the moving measuring element, in direct proportion to the amount of water that passes through the meter. The piston or disk moves a magnet that drives the register. They operate, by isolating and counting known volumes of a fluid, while feeding it through the meter. By counting the number of passed isolated volumes, a flow measurement is obtained. These meters are suited for measurement of clear water with little turbidity and are less expensive than non-mechanical types. They are generally fully accurate at the low-to-moderate flow rates, typical of residential and small commercial users and are hence common in urban water supply systems. However, they have higher maintenance requirement.
Electromagnetic meters: Electromagnetic meter is a non-mechanical meter, mainly used in urban water or wastewater or industrial systems. These are also known as “mag flow” meter. Technologically, these are velocity-type water meters, except that they use electromagnetic system for determining the water flow velocity. Mag meter uses the principle of Faraday's law of induction for measurement and require AC or DC electricity from a power line or battery to operate the electromagnets. Since Mag meters have no mechanical measuring element, they normally have the advantage of being able to measure flow in both the directions and use electronics for measuring the flow. Mag meters can also be useful for measuring raw (untreated/unfiltered) water since there is no mechanical measuring element to get clogged or damaged by debris flowing through the meter.
Ultrasonic water meter: Ultrasonic water meter uses an ultrasonic transducer, to send ultrasonic sound waves through the fluid, to determine the velocity and translate the velocity into measurement of the water volume. The ultrasonic meter has a sensor that can be either inserted inside or attached outside of the pipe. The sensor measures the water velocity in the pipe and then converts this into flow rate. Ultrasonic water meters are typically very accurate. In addition, they have wide flow measurement ranges, require little maintenance, and have long lifespans due to the lack of internal mechanical components to wear out.
Selection of Water Meter
Selection of water meter involves both size and type of meter, which is decided by the anticipated range of flow rates, plus allowable pressure loss and possible safety requirements.
Other factors to consider are location where meters will be installed, special protection requirements against weather, vandalism, tampering or particular provisions for reading.
When selecting a meter, it is necessary to assess, the consumer’s probable demand rates (average flow and maximum flow requirement ), diameter and materials of the existing pipe, impacts of water quality (corrosion, presence of sand or other suspended solids, scaling, dissolved air, temperature), effects of soil and environment aggression (temperatures, humidity, snow), tariff system and frequency of reading, inspection or replacement routines, risks on transport or due to installation and bad practices (wrong position, inverted flow, tampering by people etc).
Other issues affecting decision are: convenient stock for replacements (number of meters, models and their spare parts to be kept in reserve); available budget (acquisition, certification, storage, transport, installation, inspection, tests etc.), financing sources and legal and contractual terms and conditions.
Smart Water Metering
A Smart Water Meter is a normal water meter linked to a device that allows continuous electronic reading and display of the water consumption. It is not necessary to manually read the meter dial. Once this information is available as an electronic signal, it can be captured, logged and processed like any other signal. Mobile phone technology, wireless modems, the Internet, and other data distribution technologies, make it possible, to bring this signal readily to a computer. Hence a Smart Water Meter can also be labelled as a “water meter on your desktop”. Following figure shows the available data transfer options for Smart Water Meters. Generally, readings are taken every 15 min, even though most systems allow for far more frequent readings.
Data Transfer Options for Smart Water Meters
A smart water meter shows the water consumption in real time. It can generate alarms for excessive use. It identifies abnormalities as they occur, so that a facility manager can take an action, to conserve precious and increasingly expensive water. It helps to understand water consumption at a site and derive corresponding water saving actions from it. Smart Water Meters provide the robust platform, upon which any integrated water management system can be built.
Need for Smart Water Metering in India
India’s population is outgrowing its water supply. According to UN report, India is set to overtake China as the world’s most populous country, in less than a decade and by 2050 it will have added 416 million urban residents. As per the study carried out by the federal government think tank NITI Aayog, 21 Indian cities will run out of groundwater by next year, including the capital New Delhi and the information technology hub, Bengaluru. According to Central Water Commission (CWC) report 2019, water levels in 91 major reservoirs in the country are at just 25% of capacity, 30% lower than last year, and 25% less than the average storage in a decade.
Growing demand for water implies the need for an improved understanding of our resources and the ability to manage that demand in an equitable and sustainable way. To tackle this ever-growing water problem, India needs lots of investment and technology upgradation such as water digitization and smart water metering etc.
Benefits of using smart meters
Improves End-Use Analysis and Efficiency: By capturing high-resolution data from individually metered households and network zone meters, departments as well as consumers are able to gain an understanding of daily and seasonal residential consumption patterns. This information is useful for optimizing operational processes and planning for network improvements. The data is also critical for integrated resource planning, demand forecasting and the design, implementation, and refinement of demand management programs.
Improve Feedback and Customer Service: By providing more information about water use, smart metering technique provides an opportunity to improve water literacy within the community and empowers household to develop a greater understanding of their consumption. For instance, rather than estimated (average) daily use based on historical consumption data, smart metering can offer real-time monitoring of consumption .
Improve Network Efficiency (Leaks, Pressure, Illegal Use and Non-Revenue Water Management): 24/7 access to water usage data plus alerts allows you to discover leaks, the day they occur. Smart metering improves the revenue recovery, by registering the exact quantity of water that is used.
Easy Billing: Error-free, automated online billing for sub-metering of apartments and tenants. Individualized billing options give the customers, easy access to manage and pay their bills without disputes.
Enable Remote Accessibility: Remote accessibility attempts to address issues of inaccessibility, labour costs, and occupation health and safety risks associated with manual meter reading.
Prevent Damage to Property: Leaks are detected fast with fewer chances of service disruptions, flooding, bursts and other water damage.
Cost Reduction: Smart meters can reduce cost by error-free operation, accurate pricing, inhibiting losses through the leak and improving efficiency.
Comparison between Conventional and Smart Water Meters
Water metering has a huge and more influential presence in the urban water sector. The relatively recent Smart Water Metering technology provides, high resolution and frequent water consumption data which can be used to improve feedback to consumers and enhance water conservation and management.
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