The benefits of AMI for water utilities is pretty well understood in terms of automating meter reading and advance billing systems. Yet as systems are deployed and new AMI-based data analytics applications evolve, utilities are now relying on new tools to mine this rich data source to reduce water loss and increase revenues.
There?s plenty of data explaining the scope of non-revenue water (NRW) loss that can account for more than $2.6 billion in lost revenues for U.S. water utilities each year. An analysis from the American Water Works Association (AWWA) shows a complex combination of unmetered or unbilled consumption factors, along with an array of meter misreads or pure leakage, all contributing to this problem.
Assessing the exact combination of these factors and deciding how to deploy time and resources to fix a particular set of problems is inherently unclear. Yet any water utility with an advanced metering infrastructure (AMI) communications network may already have the necessary tools to mitigate the impact of unauthorized consumption, unmetered consumption, meter inaccuracy and leakage.?
Water Balancing Recaptures NRW
Again, the AWWA estimates that at a minimum, most water utilities lose between 10 and 15 percent of their water resources to non-revenue loss. In some markets, utilities may lose up to 50 percent through a combination of authorized and unauthorized consumption, apparent loses through theft or meter reading inaccuracy, and real loss from transmission mains right up to end-point connections.
Water balancing analytic tools, based on AMI data, provide insight into ?unbilled meter consumption? due to meter inaccuracy and water theft. By collecting hourly data at multiple metering points along the network ? from production points such as wells or bulk water supplies and other key points along the distribution, to end user meters ? water utility operations teams can pinpoint problems at a single meter, or identify trends across thousands of units. Is a shut off meter still producing water due to a constant leak or intermittent but unauthorized consumption? Is there a gap in output versus consumption between a major junction compared with the collective use in a neighborhood? Could there be an authorized, unbilled user consuming water over and above their planned allotment?
New AMI analytic and geospatial mapping tools can readily compile and analyze consumption data at a single point or macro view to let water utilities quickly respond to site-level individual problems, or better plan and allocate their maintenance and capital resources.
Meter Trending Pinpoints Meter Repairs
AMI-based analytics also create visibility on the condition and performance of meters in the field. Traditionally the meter management team does the time-consuming task of pulling, testing and recalibrating 50 or so meters back at the shop. They then extrapolate maintenance or replacement schedules based on that small sample. But 50 out of tens of thousands of meters is a poor metric that cannot accommodate for real-time condition changes.
Earlier AMI systems may let meter shops see if meters are working ? on or off ? but do little to offer condition or performance data. Active visibility across and entire meter network allows for new and powerful trending analysis to spot anomalies of one meter against a local cluster of meters so maintenance crews can? zero in on a repair or replacement. The same tools may trend performance of meters over time, which is a better predictor to plan for replacement schedules compared with random sample projections.?
The District of Columbia Water & Sewer Authority (DC Water) uses meter data analysis to eliminate the number of field tests that actually need to be performed, saving the utility significant costs.
?If you do the math on large meter tests, the fully loaded cost on this type of program is about $350 to do a single meter test,? says Charles Kiely, assistant general manager of Customer Care & Operations for DC Water. ?That?s an expensive program to implement when most of your meters are accurately recording consumption.?
Targeting meters that appear to be failing, rather than setting up a schedule that tests a sampling of meters on a regular basis is more cost-effective and efficient. ?Instead of testing them all to find the few that failed, let?s target those that we suspect of failing using the data that we?re collecting from AMI,? says Kiely.
AMI Data for Customer Service?and Water Conversation
A more accurate and timely meter and water consumption analysis based on hourly AMI data also helps utilities work with their customers to conserve water resources. In many cities and towns, water utilities are linking this data to powerful, real time email alerts. ?We use AMI data to transition from reactive to proactive mode,? says Josh Wedding, water operations manager in Redmond, Ore. ?When we see customers losing water, we can dispatch a tech with a smart phone, send customer email alerts, hang door tags or make phone calls,? he said. ?We?re always finding new reasons to like AMI.?
Because Redmond has a large number of accounts like warehouses, commercial properties and residential rentals that move from active to inactive for an extended period of time, the utility uses AMI-generated data to alert property owners of water usage, leaks or damaged pipes on vacant accounts that could result in property damage. Landlords can then shut off water and make any necessary repairs based on information that normally wouldn?t surface until the end of a billing cycle.
Meter Right-Sizing Improves Meter ? and Billing ? Accuracy
Big data collected by new AMI systems is also creating powerful tools for finding value in small things. A major NRW culprit is often just the wrong meter size for the wrong application: contractors installing a one-size-fits-all meter in multiple locations, especially in commercial sites; or a residential plumbing design that didn?t account for future water use of a new sprinkler system, swimming pool or a growing family. These and other factors often result in the wrong meter being over or underspecified for a particular setting. A meter with a larger diameter pipe of, say, 1-in., might have a low flow condition that under-registers consumption flowing to a 5/8-in. connection. Conversely, an undersized meter-to-pipe ratio may not accurately read the resulting high pressure flow and give an under-flow reading.?
A misread of a few percentages above or below the AWWA recommended standard of +/-5 percent has a dramatic effect on meter accuracy and lost revenue. A study for one Aclara water utility partner found meter sizing errors of between 5.5 and as low as 0.5 percent for its top 20 commercial customers. The resulting under-reads over the course of the year represented a staggering $400,000 in lost revenue.
AMI Networks Carry Water Main Leak Data ?
The EPA estimates that water lost due to leaky or broken pipes costs the United States some $2 billion a year in wasted treatment and pumping costs. Coupling AMI communications networks with advance acoustic sensors can give water utilities new visibility into leaks and potential breaks in their water mains. The acoustic sensor is magnetically attached to values at regular intervals. Analyses and communications are sent back, via the AMI network, isolating the location and characteristics of mechanical vibrations caused by a leak or full rupture.
?We?re averaging a leak a day, and more in the winter months,? says Curt Cochrane, DC Water?s water operations manager. ?That adds up to about 500 water main leaks a year.? Washington?s joint leaks are difficult to find because many of the city?s water mains are located under streets that are surrounded by other underground utilities. In this environment, a leak may follow along the pipe underground until it reaches a sanitary sewer, electrical vault or some other point of easy escape.?
In a pilot program, Cochrane?s team successfully found one leak that was subsequently verified and repaired, and pinpointed the location of another probable leak in the same area. The acoustic-based system was better at picking up leak noise than other methods, according to Cochrane, who also noted that the devices on the service lines in the same area did not detect the leak. The utility is now placing loggers in areas where the utility suspects there may be leaks. Once leaks are identified and repaired, the utility will move to the next trouble spot.
The bottom line is that leaks add up. According to Cochrane, up to 20 percent of the water pumped into DC Water?s distribution system never makes it to customers? meters. This unaccounted for water can be attributed to a number of factors but unidentified leaks represent a significant portion of unaccounted-for water.
Using massive data analysis and tools to harness information from simple AMI reading applications can further leverage the value and investment of a water utility?s AMI network. Today, AMI is as much about getting the data a water utility needs to power new applications and services as it is about meter reading. It?s about using data-driven information to leverage an AMI investment to improve existing services and manage a water distribution network. With complete web-based visibility across the entire distribution system, utilities have a new level of information and control over their resources, assets and revenue.
Larry Murphy is senior director of Customer Systems Engineering at Aclara.
