Flat Rock Springs was a peaceful, pleasant part of the landscape.
Unfortunately, it was not a natural spring.
In reality, Flat Rock Springs is a relatively low-flow leak that had spilled 250 million to 500 million gallons since the late 1980s, according to Tennessee’s White House Utility District (WHUD), a municipal agency north of Nashville.
Leakage, or nonwater revenue loss, is a chronic and growing problem for water utilities. On average, a utility should expect to lose around 10 percent to 15 percent of its water on the voyage from the treatment plant to the faucet. Unfortunately, the total is often much higher.
Globally, the World Bank estimates that the world collectively loses 32.6 trillion liters of water a year, or nearly enough to fill China’s Three Gorges Dam to the brim every year with clean, treated water.
The Source of the Problem
Why is so much water being wasted? There are several reasons. Water networks are often old (20 percent of San Francisco’s water lines are over 100 years old), spread out across thousands of square kilometers and underground. Additionally, budgets are tight and customers are exceedingly demanding. Water has to be there. No one wants their shower to be only “17 percent loaded” like on Netflix.
The problem gets even worse in emerging nations. Approximately 45 percent of the people in the world live in drylands, defined as regions that get 600 millimeters (mm) or less of rain a year, according to Alon Tal, a professor at Ben-Gurion University.
Saving Wasted Water
Here is the good news: leakage can be fixed. In fact, water recovery has become one of the cheapest forms of sourcing water. Bluefield Research estimates water from leaks costs on average $1.21 per 1,000 gallons in the United States, less than half of the cost of traditional water.
The techniques for reducing leakage vary. WHUD, for, instance, previously used acoustic sensors to try to locate drips. As you can imagine, it was often time-consuming and inefficient. They could hear leaks, but they were not easy to pinpoint.
In 2015, the utility district took a new tack. It planted flow meters across its service to get visibility into water consumption on a roughly block-by-block basis. WHUD invested in meters; data capture and synthesis software that captures and organizes data so employees understand water consumption and where it is taking place; mapping; and installation. This software captured and organized data so employees could easily understand what was going on.
In a clever twist, WHUD did not track daytime use. Instead, it compared inflow and outflow between 1 a.m. and 4 a.m. Daytime use varies; some people use far more water than others. But nighttime use, WHUD reasoned, should be consistently low. Any street or address where consumption was more than 26 gallons per minute (gpm) was a strong indication that the people living there were either insomniacs who bathed quite a bit in the middle of the night or, more likely, living next to an underground, undetected leak.
Within three days, the utility found a leak that was losing 280 gpm, or enough for 2,239 homes for the region. People thought it was a stream.
In 2015, WHUD found and fixed leaks that were costing $400,000 of water per year. The next year, it recovered $900,000 with more leaks, bringing the two-year total to $1.3 million. In 2017, close to $400,000 more worth of water was found. These efforts have allowed WHUD to postpone a $15 million to $20 million upgrade, which would have cost the utility $600,000 in interest payments alone per year. WHUD now believes it will not need substantial capital upgrades until 2028.
“Our water treatment plant was having to run one hour a day just to feed that leak,” WHUD geographic information systems (GIS) director Carl Alexander said. “Without us knowing there was a problem in that area, we would have never been able to stumble upon it.”
Use Data to Tap into Savings
Maynilad in Manila did something similar, but on a much larger scale. It used flow, pressure and other data from meters and sensors to precisely triangulate the location of an underground leak. Unusual declines of pressure or flow were taken as symptoms of a leak. Over the next few years, leakage was cut in half and the number of people living in Manila who were getting adequate service over the full day rose from around 50 percent to more than 90 percent. Pinpointing the source of leaks also reduced the cost of repairs by reducing the amount of leaks. Fixing some leaks has dropped from $1.7 million to $1,250 per leak.