Resilience Scanner

Automated Water Meter Infrastructure for Real-Time Leak Detection

Solution Overview

San Francisco's automated water meter infrastructure enables real-time leak detection and customer notification to reduce water waste across the city's 170,000 retail customer accounts.[1][9] The San Francisco Public Utilities Commission (SFPUC) was the first large utility in California to fully automate its meters, allowing it to provide more timely water use data to customers.[3] For more than a decade, SFPUC has used advanced metering infrastructure (AMI) to collect hourly water meter readings from all retail customers.[2]

Technical Components

The automated water meter system employs the Aclara STAR Network technology, which uses low-frequency radio signals to collect hourly water use and transmit that data four times daily to the SFPUC billing system.[7][5] A total of 81 Data Collection Units are located throughout the city on SFPUC facilities and City-owned poles and rooftops to transmit the meter readings to the SF Water, Power and Sewer's AWMP database.[8] The new meters track consumption and send the data wirelessly to the San Francisco Public Utilities Commission four times a day.[6] The system provides frequent transmission of more precise water consumption data allowing for quicker and more precise identification of high usage and suspected leaks through a leak detection notification program.[8] The SFPUC partnered with the Department of Public Health to complete an evaluation of RF transmission levels associated with the Meter Transmission Unit System, which confirmed that the signals are well below government limits with respect to human exposure to RF energy.[8][7]

Implementation Details

San Francisco started replacing its 175,000-plus water meters in June with high-tech devices as part of the SFPUC automated water meter program, a two-year effort that began on June 7.[7] The San Francisco Public Utilities Commission began citywide installation of the Aclara STAR Network system in early calendar 2010.[5] The program, launched on May 21, has placed the meters in 180,000 homes and businesses as California tries to cope with an extended drought.[6] San Francisco has spent $56 million on smart water meters that allow residential and commercial customers to track how much water they're using.[6] The $50 million program is being funded by a 91-cent fee that's being tacked onto ratepayers' monthly bills.[7] SFPUC hired Woodard & Curran to help develop a system of detecting possible leaks for large multi-family buildings and CII accounts with more certainty.[2] Woodard & Curran partnered with local civil engineering firm Lotus Water to collect, analyze, and report on water use trends for SFPUC's large retail water service customers.[2] The customer Web interface for viewing water usage online is under development and is expected to be available within two years of deployment, though the exact timeframe is uncertain.[7]

The Leak Alert Program provides proactive customer notification of potential on-site leaks based on meter data.[4] The notification system leverages a customized version of the communications software SFPUC uses for emergencies and runs automatically.[2] Notifications are sent through all available communication methods, first prioritizing SMS text and email, followed by automated phone call and mailed letter.[2] Account holders for single family and small multi-family homes in San Francisco are automatically alerted of a potential leak if usage is consistently more than one cubic foot (about 7.5 gallons) every hour in a two-day period.[2] The Leak Alert program alerts customers when they have three days of non-stop water use, which could indicate a plumbing leak.[3] For commercial, industrial, and multi-family properties more than three dwelling units, the SFPUC also screens for increases of 50 percent and more in water use over the past 90 days, as well as spikes in nightly water use, in addition to constant use monitoring.[3]

The expanded leak detection program employs two criteria for identifying potential leaks. The first criterion takes the average number of hours of zero consumption from 1:00 to 4:00 a.m. over a 90-day period to sort accounts into two categories – those that tend to have no consumption overnight and those with continuous use comparable to other hours of the day.[2] The second criterion is the ratio of consumption from 1:00 to 4:00 a.m. on the last two days divided by the average use in the same hours within the prior 90 days, where spikes in the ratio indicate an increased water usage during typically low-usage hours.[2] The expanded leak detection program notifies customers with intermittent overnight use of a possible leak when the resulting nighttime consumption ratio is greater than 2, and for properties that usually have regular overnight use, the criterion triggers a notification when the ratio is greater than 4.[2]

Benefits and Impacts

San Francisco deployed automated water meter technology estimated to save 54 million gallons per year notifying customers about leaks.[9] The total savings across the leak detection program (including single family, small multi-family, and irrigation accounts) is approximately 76 million gallons per year.[2] In the last fiscal year, the Leak Alert program saved SFPUC customers an estimated 47 million gallons of water.[3] Since adding large multi-family units and CII accounts to SFPUC's leak detection program, the agency has realized an additional 30 million gallons of water savings per year.[2] The leak detection program represents a 20 to 50 percent reduction in volume of water lost due to leaks, depending on the customer sector.[2] The San Francisco Public Utilities Commission's Leak Alert Program has a goal of saving 0.1 MGD (million gallons per day) between 2020-2025.[4]

Of those notified in the last year, 88 percent stopped constant use within four weeks.[2] Approximately 11 percent of CII and 19 percent of large multi-family accounts are notified of a potential leak every year.[2] The King George Hotel in the City's Union Square District is one the local businesses that has benefitted from the expanded Leak Alert program, as the SFPUC notified the hotel after analyzing water usage data, which indicated that the business was using more than 200 gallons per hour of water than typical.[3] Hotels make up approximately 6 percent of SFPUC's commercial accounts, but use more than a quarter of total commercial consumption due to extensive laundry, dishwashing, cooling, and kitchen operations, amenities such as pools and restaurants, and large number of overnight guests.[2]

San Francisco residents can register for My Account to track water usage data, view daily and hourly water usage, identify unusual spikes in water use, and receive notifications of possible leaks faster by updating contact information with cell phone or email.[1] San Francisco customers who register to pay their bills online through MyAccount also can track their water use on a daily or even hourly basis to detect water waste.[3] Consumers can look at the information as it's received and compare consumption to past use as well as city averages.[6] Most San Francisco residents use about 40 gallons of water per person per day, which serves as a baseline for identifying unusual water usage patterns through the My Account system.[1] Customers will eventually be able to log on to their own accounts with the SFPUC to monitor their own water consumption habits and billing.[5]

The automated water meter system eliminated the need for manual meter reading, as currently most residential water meters in San Francisco are read once every two months and commercial meters are read monthly, with meter readers required to individually visit and read each meter manually.[5] Aclara said the manual meter reading process makes it difficult to detect silent leaks, which can result in significant water loss and high water/sewer bills for customers.[5] SFPUC General Manager Ed Harrington stated that automated meters will give the SFPUC and customers more accurate information about water consumption that will help detect leaks faster and conserve more.[5]

Climate Adaptation Relevance

The automated water meter infrastructure addresses water scarcity challenges intensified by extended drought conditions in California.[6] The Environmental Protection Agency estimates that the average household's leaks can waste nearly 10,000 gallons of water every year, and 10% of homes have leaks that waste 90 gallons or more per day.[1] By enabling rapid leak detection and customer notification, this system helps conserve limited water resources during periods of climate-driven water stress.

Business Analysis

Large multi-family buildings and CII accounts constitute 54 percent of San Francisco's water consumption, representing a significant market opportunity for water conservation interventions.[2] The San Francisco Public Utilities Commission's Leak Alert Program is an ongoing program that continues to be implemented in-house.[4] The program operates through a customized version of the communications software SFPUC uses for emergencies, leveraging existing infrastructure to minimize operational costs.[2] The automated water meter system was funded through a $56 million capital investment, with a 91-cent monthly fee added to ratepayers' bills to support program financing.[6][7] This fee-based financing model distributes costs across the customer base while enabling immediate implementation without requiring upfront municipal bond issuance.

Sources