Memphis, Tenn., bears the nickname the “Home of the Blues.” And, while the history of the blues may date back to the early 20th century, the water that comes from the aquifers beneath the second largest city in Tennessee is pulled from geologic strata believed to be 40 million years old.

With this in mind, it was with a great deal of pride that Memphis was recently recognized as having the purest drinking water in the United States.

“Memphis is the largest U.S. city to rely 100% on groundwater for its water supply,” noted Chandrika Winston Rosser, vice president of Gas and Water Engineering and Operations for Memphis Light, Gas and Water.

Other U.S. urban areas that use aquifer water include Dayton, Ohio; Miami and Jacksonville, Fla.; Nassau and Suffolk counties in New York; San Antonio, Texas; and Spokane, Wash.

The purest drinking water distinction was awarded by the Environment Working Group Tap Water Database. Launched in July 2017, the online resource spreads awareness about drinking water quality in the United States and gives users the lowdown on what’s in their tap water.

Responding to the accomplishment, Rosser said, “We are very fortunate to have such a wonderful natural resource. We work very hard every day to preserve its integrity.”

The 100-trillion-gallon aquifer that provides water to MLGW’s 257,000 customers is the size of Lake Ontario and is believed to be the result of a shift in the continental plates 100 million years ago. According to scientists, wind and erosion shaped the impression that became the aquifer, and a river that was the predecessor of the nearby Mississippi River deposited sand that formed the aquifer and filters the water to remove impurities and solids.

The water in the aquifer is estimated to have fallen as rain about two to three thousand years ago, estimates the University of Memphis Center for Applied Earth Science and Engineering Research. Newer water continues to enter the aquifer at recharge points outside Shelby County, where Memphis is located, Rosser said.

The Environmental Protection Agency and the Tennessee Department of Environment and Conservation have developed standards for contaminant levels in drinking water. While all water contains slight levels of contaminants, Memphis water has especially low levels of fluoride, nitrate, lead and copper. In fact, a 2015 MLGW report noted that Memphis had no “detectable lead” in the source water.

What that means is the Memphis water treatment process is much simpler and less expensive than the average urban water system. Rosser explained that the water is aerated and filtered to remove naturally occurring iron, disinfected with sodium hydrochloride, and finished off with tooth-strengthening fluoride and phosphate to prevent pipe corrosion.

In addition to exceptionally pure drinking water, Memphians benefit from their underground resource with residential water rates that are among the lowest in the United States.

The Memphis water supply story dates back to the decades after the Civil War when the area was ravaged by a yellow fever epidemic. After determining that the deadly illness originated in the water, city officials determined that the open cisterns and shallow wells that provided water to residents were breeding grounds for bacteria and mosquitoes that spread the illness.

In 1886, while drilling a well that still supplies water to Memphis, the drill punched through a layer of clay, releasing the ancient water that was below. Clear, cold water sprang out in a geyser, and the city’s sweet water supply was born.

MLGW performs approximately 100 tests each day to monitor the water quality in its 10 pumping stations and 175 wells.

“We work very hard to ensure that the water remains clear of contaminants from urban, industrial and agricultural runoff,” Rosser said. She noted that MLGW was founded in 1939 and is not only the largest three-service municipal utility in the country but operates one of the largest artesian well systems in the world.

In addition to the municipal wells, there are also private wells that supply residences and local businesses. These include several country clubs, some industrial sites and a few breweries that have capitalized on the pure drinking water.

Rosser said the county’s Groundwater Quality Control Board oversees permitting for wells to ensure the continued safety of Memphis water. Additionally, public policies have been put in place to protect water quality. She added that education of the public is also an important piece of maintaining the safety of the water supply.

In addition to water quality, there is always the question of depletion of the natural resource. Rosser said the U.S. Geological Survey monitors water levels in the aquifer. In the decades after the first wells were drilled, as the population of Memphis grew, the water levels in the aquifer began to drop, but since the turn of the 21st century, the water levels have started to rise. While climate change has been blamed for water levels rising around the world, Rosser said modern household plumbing and appliances have also helped keep plenty of water in the aquifer. Low-flow toilets now use about 25% of the water per flush as opposed to older models. New faucets and washing machines contribute to the reduced demand for household water not just in Memphis but throughout the country. And while some companies are bottling water to sell, Memphis residents are happy to enjoy water straight from the tap. Rosser noted, “Among my colleagues, we talk about how we can tell the difference when we’re away from here. We can’t wait to get home to have Memphis water.”

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