The water meter is the proverbial cash register of the water industry. We need meters to measure the consumption of fresh water to residence, corporate, and industrial users.
There have been and continue to be many options when it comes to billing for fresh water.
Decades ago, there were just flat rate billing. Every residence paid exactly the same rate per month for fresh water. It was a means to recover costs for the purification and distribution of fresh water. But not every residence was the same, so it was often seen as an unfair process. If one home was occupied by a single person and the next home was a multi-generational family of 7 or 8 people, the volume of water used was very different, yet the billing was equal. So, it was understandable that ratepayers pushed back against this approach.
Manual Meter Readers
Next, we hired people to go around door to door to manually read the water meters. In the early analog days this required a worker to visit each home, gain access to the meter, and then write down the consumption flows from the analog dials of the mechanical meter. Access was not always possible so the manual reads were sporadic and the time and water flows were extrapolated to estimate an average monthly consumption value. This provided a means to forecast and predict what might be the water usage for the coming month and when possible, these predictions were corrected with physical reads from the analog meter. So, ratepayers had correction adjustments on their bills that could reduce the future bills to level out the actual consumption or more likely increased the bills causing more upset.
Remote Displays and Touch-pads
In many cases, accessing a water meter installed in a basement, tenant apartment, or underground pit proved to be challenging. So, the next logical evolution was the remote. There were two types of remotes. One was a remote display that simply repeated the values seen on the analog meter itself. These remote displays could be visually read by anyone outside the residence. They used pulses to count water volume so there was a level of inaccuracy in these mechanical displays. Eventually these pulses were digitally encoded and the displays were upgraded to numerical digital readouts. The accuracy was better but it was still pretty manual. Values were written down by the Meter Reader staff and mistakes happened. Later, handheld devices replaced the notepad and this allowed for electronic transfer of the many daily reads at the end of the shift.
Shortly after the remote display came along, some clever folks developed the digital touch-pad, which is still around today in many smaller communities. Touch-pad or touch read based meters have an induction coil-based reading pad that is mounted outdoors and wired to the meter’s encoder registers. The meter reading is obtained by a reading devices or wand. A simple touch reader like the EasyProbe simply reads and displays the meter on a handheld device. There are other devices like the Kemp Meek MP-70101C and MP-70101D which can store readings in memory for download to a computer. The models MP-70101A and MP-70101B can display readings or with a cable transfer them to a handheld meter reading computer. The digital age was finally here.
Now that encoded water meters could be read digitally and transferred to the operator’s computers for billing, the accuracy improved. The efficacy of the field reading process greatly improved and the quality of the billing reflected the digitalization of the workflow.
Automatic Meter Reading
Innovation did not end and the next idea to develop was AMR or Automatic Meter Reading. It was still challenging for workers to access the property even with the advances for remote displays and touch-pads. Homeowners planted shrubs, built fences, discarded items around the outdoor terminals, and had territorial dogs ready to guard their property from unknown intruders. While access was greatly improved and accuracy was now stabilized, it still needed more. With AMR, the Meter Reading staff could simply walk by the homes and capture water meter reads from the sidewalk or curb without ever actually setting foot on the property. Sometimes foul weather or overgrown bushes prevented the Meter Reader from obtaining timely reads, but this was far less of a problem then in the previous scenarios.
Advanced Meter Infrastructure
As technology advanced, AMR evolved from the slower and physical walk-by scenario to a faster, more accurate drive-by approach. Work trucks were outfitted with rooftop antennas and had large screen displays and computing terminals installed. The use of digital maps planned out the drive routes to ensure every customer had their meters read. With faster CPUs and more RAM memory, these radio-based AMR solutions were faster, more accurate, and interactive in real-time so the Meter Reader had red and green flags showing which homes were successful read and which homes failed as they followed the GPS guided routes. Whole cities had their water meters read swiftly and accurately. For smaller communities this model is still one of the most effective means to capture accurate water consumption values.
Today, the next generation of AMI (Advanced Water Infrastructure) is being deployed. Due to the capital costs, smaller communities, towns, and cities are still finding the AMR approach to be more cost effective. But AMI which was once relegated to major cities is not becoming available to smaller municipalities too.
Wireless Network Topologies
A modern AMI solution can use a variety of wireless network Internet of Things (IoT) architectures, including Star, Mesh, and Cluster Tree. Many are closed architecture, propriety offerings which lock the municipality into a single vendor option, which is problematic. A few are open architecture which permits Cities to tender for water meters and even mix vendor meters as required, not just for residential water metering but for corporate and industrial water metering too.
The Star topology is often the simplest to deploy, but wireless coverage can be challenged with obstructions to clear line of sight. Star topologies that use the LoRa wireless solution offer longer range albeit at a lower data rate. For water metering applications, LoRa works well. It is affordable for smaller municipalities too.
For medium sized and larger cities, the Cluster Tree topology has unique advantages over the Star model. It permits in-band repeaters that bend radio signals around obstructions. While the Star topology prefers taller rooftops, water towers, or telecommunication towers to launch from, the Cluster Tree can leverage lower height assets including streetlight standards that can provide about 10 to 12 metres of elevation above grade levels and already have access to AC power to energize these gateways and repeaters.
The Mesh network is best for comprehensive coverage, but needs a number of smart city applications to warrant the higher costs for the comprehensive infrastructure. It can soon be used for reading water, gas, and electrical meters, as well as for advanced dimming streetlight automation, dynamic traffic lights, transit digital signal, garbage bin location and volume reads, kiosks, and many other valuable smart cities use cases. The capital costs and the operating cost for a Mesh network are higher, but then so is the Return on Investment and ratepayer satisfaction levels when deployed well. There have been some public safety enhancements to these Mesh networks for CCTV surveillance systems and even gunshot detection that triangulates and pinpoints the firing of a weapon for immediate police response.
So, these Mesh networks are for far more than just reading water meter consumption. Added value capabilities in the water industry to detect water leaks and measure water pressure throughout the distribution mains is now readily available. Even remotely detecting water quality throughout the distribution pipework is possible. All of this data is retrieved in real-time of near real-time. This real-time aspect drives better and faster decision-making and saves money and prevents undesired repairs due to prolonged leaks.
Historically, meters were mechanical in design. Later, they used magnetic fields to detect flow of water. And, more recently, they make use of ultrasonic sensors to detect flow. The older mechanical meters where analog devices whereas the latest ultrasonic meters are almost all digital end to end.
Common types of meters include:
- Displacement Meters also known as Positive Displacement (PD) meters or nutating disk meters
- Jet meters (single and multi-jet)
- Turbine meters
- Electromagnetic Meters, often simply called Mag Meters
There are various manufacturers of radios, with the most popular brand being from Itron. These radios are called ERT, which is an acronym for Encoder, Receiver, Transmitter. The ERT can be integrated with the water meter. However, since most water meters are installed in basements or pits, this means that the radio is also collocated in these positions. It is difficult for the radio to connect from these positions. So, a two-piece solution was developed that saw the water meter and the radio packaged as two devices connected by a simple three wire cable.
In a two-piece package, the radio can be installed higher up instead of nearer to the basement floor or inside the pit. This permitted the radio to still be protected inside the basement but located in the rafters of the ceiling so the connectivity was improved. The radio can also be installed outdoors with the connecting cable penetrating the exterior wall. By mounting the radio outdoor and 1 to 2 metres above grade level, the signal connectivity is greatly improved. It can be post mounted external of a pit too. If the radio signal does not need to penetrate the house’s walls, the propagation and signal capture is dramatically improved.
In North America, including here in Canada, the spectrum most commonly used is the ISM (Industrial, Scientific, and Medical) band. It is from 902 MHz to 928 MHz. The radio signals are modulated on spread spectrum carriers. The ISM band is offered licence exempt so it is a shared spectrum resource which can create interference concerns but carries no annual fees from the domestic regulator.
In some cases, lower frequencies in the licenced spectrum range are used compared to the traditional ISM band, with tiny fixed carriers are also used in the 450 MHz to 470 MHz spectrum. These are narrowband signals with limited data rate but excellent propagation characteristics. Annual licencing fees are required for use in this spectrum.
Regardless of how the data is captured and transferred, it ultimately ends up in a headend solution, often called a Meter Data Management (MDM) platform. Management and configuration of the datagrams as well as the network is controlled from the headend. Data can be parsed for duplication, data integrity, and missing meters whose consumption data is not delivered can be requested to resend the data or will be flagged for the AMR walk-by or drive-by solutions. If an AMI wireless fixed network is used, then a re-transmit request can be issued to the missing meter to resend its datagrams.
The MDM platform is often connected via APIs to a variety of other important IT platforms. These can include:
- ERP platform for billing and accounting
- CRM platform for customer tracking
- AI and Analytics platforms for understanding the data flows
- Customer presentment platform so data about consumption and costs can be shared with the ratepayer via handheld smartphones, tablets, and computers
- Open Data portals to make anonymous data publicly accessible
The data is critical for monetization and for cost recovery for the municipal operators. Other features for residential endpoint leak detection, water main break detection, and water quality are evolving to go along with the standard water consumption reads.
Water has always been the source of growth and dispute between providers and consumers. Nowadays, water conservation and environmentally friendly technologies are becoming more important, especially in areas where access to water is expensive or restricted. Since water has become a limiting resource for economic development, accurate measurement of consumption is important for both trade and industry. Unfortunately, over time and use, the internal components of a analog, mechanic measuring flow meter wear, and the level of metering accuracy drops. This progressive drop in metering accuracy causes “meter drift”. The newer digital water meters are more trustworthy and provide consistent accuracy over the end-to-end lifespan of 15 to 20 years.
In such high-volume consumer system, a small drift may result in lost revenue due to an under-accounting of the quantity of used water. In such systems, in order to endlessly repair, rebuild, or re-calibrate all the flow meters a labour intensive and expensive process is required that causes significant down-time too. In the new digital water meters, the sustainability of the system is greatly enhanced.
Using a fixed wireless network, the efficacy of the collection of water consumption is improved and coupled with the enhanced accuracy, the water metering solutions are now to a state of high performance.