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Automated Water Meter and Leak Detection System

Solution Overview

The San Francisco Public Utilities Commission deployed automated water meter technology and leak detection systems to reduce potable water losses from its distribution system.[3] For more than a decade, SFPUC has used advanced metering infrastructure (AMI) to collect hourly water meter readings from all retail customers.[2] The agency was the first large utility in California to fully automate its meters, allowing it to provide more timely water use data to customers.[1]

Technical Components

San Francisco Public Utilities Commission installed the STAR network from Aclara across the city's 180,000 meters to combat drought and save water through hourly meter reading.[4] The data collected from the city's meters by Aclara's two-way fixed network powers the utility's system for letting customers track usage online.[4] Aclara generates a report that allows SFPUC to identify customers who may have leaks inside their homes.[4] Most of Aclara's California customers, including SFPUC, are looking at installing the STAR ZoneScan system, which allows utilities to pinpoint underground leaks.[4] With hourly usage data transmitted from the meter directly to SFPUC systems, 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.[1] 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.[1] 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] San Francisco customers who register to pay their bills online through MyAccount can track their water use on a daily or even hourly basis to detect water waste.[1]

Implementation Details

A few years ago, SFPUC wanted to upscale its leak detection program beyond residential and small multi-unit buildings to include approximately 10,000 multi-family homes with six or more residential units and 17,000 commercial, industrial, and institutional accounts.[2] 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] Given that large multi-family buildings and CII accounts constitute 54 percent of San Francisco's water consumption, there was a massive amount of data to analyze and determine water use trends.[2] The SFPUC expanded its Leak Alert program in August 2021 to include commercial and industrial properties and larger multi-family buildings, in addition to single and small multi-family properties and irrigation accounts.[1] The notification system leverages a customized version of the communications software SFPUC uses for emergencies and runs automatically, with notifications sent through all available communication methods, first prioritizing SMS text and email, followed by automated phone call and mailed letter.[2] The utility reaches out to those who show up on the report by sending weekly postcards notifying them of a possible leak.[4] It monitors the reports and notes which accounts have come off the list, assuming that they have responded to the utility's notice and fixed the leak.[4]

Benefits and Impacts

The automated water meter technology is estimated to save 54 million gallons per year by notifying customers about leaks.[3] In the last fiscal year, the Leak Alert program saved SFPUC customers an estimated 47 million gallons of water.[1] 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] This brings the total savings across the leak detection program, including single family, small multi-family, and irrigation accounts, to approximately 76 million gallons per year.[2] Depending on the customer sector, this represents a 20 to 50 percent reduction in volume of water lost due to leaks.[2] Approximately 11 percent of CII and 19 percent of large multi-family accounts are notified of a potential leak every year.[2] Of those notified in the last year, 88 percent stopped constant use within four weeks.[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, after the SFPUC notified the hotel following analysis of water usage data, which indicated that the business was using more than 200 gallons per hour of water than typical.[1]

Climate Adaptation Relevance

The SFPUC provides drinking water to 2.7 million people throughout the Bay Area.[1] This leak detection technology deployment reduces losses of potable water from the SFPUC distribution system as part of the Innovations Program, addressing water conservation needs during drought conditions.[3] The SFPUC's water loss control program is described in Section 6.2.5 as part of DMM 5 Programs to Assess and Manage Distribution System Real Loss, with non-revenue water representing the difference between the volume of water that enters the distribution system and the volume of water that is billed to customers and comprised of both apparent and real losses.[5]

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