Unaccounted for Water and the Value of Leak Detection
While water is always a hot topic in both California and Nevada, most of us aren’t typically thinking about where our water comes from, let alone how it reaches our taps. When we are thirsty, we just walk to the sink or refrigerator and fill up a glass. We expect there to be water available when we turn on the faucet. The truth is, however, that there is quite a bit of unseen work required to make sure that the water is available when we turn that faucet handle.
One of the most important tasks is fixing leaks that can disrupt or reduce the pressure of water reaching your home or business. Sometimes these leaks are small like a running toilet or pinhole leak in a water line and won’t disrupt the supply. Others are large and can often lead to large sinkholes, significant water losses, and the disruption of service. These large leaks often surface quickly or are identified by service disruption and are fixed quickly. While small leaks might not seem important, over time they grow to be large leaks and cause significant damage if not fixed. Additionally, the small leaks can add up to significant water losses over time and often do not surface therefore continuing to leak without anyone noticing. These losses along with illegal connections, slow meters, and water used for system flushing and firefighting used to be considered unaccounted for water since the water wasn’t billed to any specific customer. This was an erroneous term that is no longer used in the industry since it is always possible to account for water losses. Now these losses are considered non-revenue water, basically water that’s wasted.
California was one of the first states to realize the importance of leak detection programs to reduce water losses. In the 1980s the State conducted a survey of water providers and determined that 770,000 acre-feet of water were lost every year – one acre foot of water (over 300,000 gallons) is the volume of water necessary to cover an acre with one foot of water – which is over seven times the water used by Portland area customers in the last year.
In response to this large loss of water, the State prepared best practice guidance to water providers to complete water audits and leak detection. A water audit quantifies the total amount of non-revenue water and estimates the amount of water lost to leaks, water theft, slow meters, system flushing, and firefighting. An assessment of validated water audit data from 2013 for 246 water utilities found that the utilities collectively incurred apparent (customer) losses equivalent to 29.4 billion gallons of water, translating into uncaptured revenue of over $151 million for the year. Additionally, the same utilities incurred 130.1 billion gallons of water lost to system leakage. This loss added over $77 million of excessive treatment and pumping expenses to utility ledgers. The number of utilities included in this assessment is a small portion of more than 50,000 water utilities in the United States; meaning water losses across all water utilities in the United States exist at a staggering level.
This is an enormous cost that is passed directly on to customers through higher water costs and connection fees. Several states now require water audits and recommend active leak detection programs when water losses are greater than 10%. An active leak detection program consists of regular surveying of underground pipes using acoustic monitoring equipment. Since small leaks often do not surface, the only way to locate these leaks is by listening to fire hydrants, service meters, or along the pavement above the water line using powerful ground microphones.
Leaks make noise because the pressurized water forced out through a leak loses energy to the pipe wall and to the surrounding soil area. This energy creates sound waves in the audible range, which can be sensed and amplified by electronic transducers. There are two main ways to identify leaks: using a ground microphone with a transducer to amplify the leak noise and filter out background noises or using a leak noise correlator which records sound at two points on a water line and correlates the location of the leak based on the time it takes for sound waves to travel from the leak to the two listening points. These two technologies can also be used together to quickly identify and pinpoint leaks. Ground microphones are more common for surveying to identify leaks while correlators are better at pinpointing leaks that have been identified.
Because of the significant water lost to leaks, all water utilities should complete water audits annually and institute active leak detection programs when losses are greater than 10%. This will not only reduce the water lost, but also reduce the energy required to provide the water and the energy costs incurred by the utilities and passed on to customers. Additionally as our infrastructure continues to age, water leaks will become more common and become a greater burden on utilities and customers.
SBC has been able to provide no-cost leak detection trainings to water agencies in the Sierra Nevada through our water energy nexus pilot program with Pacific Gas and Electric Company. Our team recently completed our fourth leak detection training with Amador Water Agency (AWA) and the City of Jackson Water Department staff. The training was completed by Utility Services Associated and provided classroom and field instruction for 13 AWA staff and two City of Jackson staff. During the field instruction 10 areas of the water system were surveyed and six leaks were pinpointed. The leaks were estimated to result in water losses of 14.7 million gallons per year. For more information on leak detection programs, please contact SBC Climate Planning Program Director, Paul Ahrns, at firstname.lastname@example.org.