Memphis, Tennessee has long been one of the luckiest cities in America when it comes to drinking water. While most major U.S. cities rely on surface water — rivers, reservoirs, lakes — Memphis draws its entire public water supply from underground. The Memphis Sand Aquifer, a vast geological formation buried beneath the city, has provided naturally filtered, high-quality drinking water for over a century.
But that luck isn’t guaranteed anymore. A combination of industrial contamination, aging infrastructure, and increasing demand is putting pressure on a resource that many Memphians have taken for granted.
What is the Memphis Sand Aquifer?
The Memphis Sand Aquifer is part of the larger Mississippi Embayment Aquifer System, which stretches across parts of Tennessee, Mississippi, Arkansas, and several neighboring states. The Memphis Sand layer sits roughly 200 to 500 feet below the surface, sandwiched between layers of clay that have historically acted as a natural barrier against surface contamination.
The aquifer supplies water to Memphis Light, Gas and Water (MLGW), the largest three-service municipal utility in the nation. MLGW operates about 160 wells across the city, pumping roughly 180 million gallons per day to serve approximately 1 million people in Shelby County and surrounding areas.
The water quality has historically been exceptional. Because the aquifer’s clay confining layers filter out contaminants naturally, Memphis has been able to deliver drinking water that requires minimal treatment — primarily just chlorine disinfection. The city’s tap water consistently ranks among the best-tasting in the country at American Water Works Association taste tests.
Where the problems are showing up
The aquifer’s protection isn’t as airtight as geologists once believed. Research from the University of Memphis and the U.S. Geological Survey (USGS) has shown that the clay confining layer has breaches — areas where surface water can infiltrate the aquifer more quickly than expected.
The most documented concern involves the Davis Wellfield, a cluster of MLGW wells in South Memphis. In the 1990s, testing revealed that water from these wells contained trace levels of industrial solvents, including trichloroethylene (TCE) and tetrachloroethylene (PCE). The contamination was linked to the former Sheahan Pumping Station area and nearby industrial operations.
The Tennessee Department of Environment and Conservation (TDEC) and EPA have been involved in monitoring and remediation efforts around the Davis Wellfield for decades. Several wells have been taken offline or fitted with treatment systems.
More recently, PFAS (per- and polyfluoroalkyl substances) have emerged as a concern. While Memphis hasn’t experienced the kind of widespread PFAS contamination seen in cities near military bases or major manufacturing sites, testing has detected low levels of PFAS compounds in some wells. The city’s proximity to industrial corridors and the Memphis International Airport — one of the busiest cargo airports in the world — makes ongoing monitoring essential.
Development pressure on the recharge zone
The aquifer doesn’t refill itself in a vacuum. It depends on recharge zones — areas where rainwater percolates through the ground and eventually reaches the aquifer. As Shelby County has developed over the decades, paving over land with impervious surfaces like parking lots, roads, and commercial buildings has reduced natural recharge.
Suburban sprawl in eastern Shelby County and neighboring DeSoto County, Mississippi has also raised questions about whether pumping rates are sustainable. A 2018 USGS study found that water levels in parts of the Memphis Sand Aquifer had declined over time, particularly in areas with heavy pumping and reduced recharge.
The concern isn’t imminent shortage — the aquifer holds enormous volumes of water. But declining water levels can change flow patterns, potentially drawing contaminated surface water downward through breaches in the confining layer. It’s a long-term risk that requires long-term planning.
What Memphis is doing about it
The city and MLGW have taken several steps to protect the aquifer:
- Wellfield monitoring: MLGW conducts regular water quality testing across its well network, including testing for emerging contaminants like PFAS.
- Wellhead protection program: The utility maintains designated protection zones around its wells to limit activities that could introduce contaminants.
- Contaminated well management: Wells that show contamination are either taken offline, treated, or replaced with new wells in cleaner locations.
- Regional coordination: Memphis participates in regional groundwater studies with USGS and the University of Memphis to track aquifer health over time.
In 2019, the Shelby County Board of Commissioners passed a resolution supporting stronger protections for the aquifer, including limits on certain types of development in critical recharge areas.
What Memphis residents should know
If you live in Memphis or Shelby County, your tap water still comes from one of the highest-quality natural sources in the nation. The Memphis Sand Aquifer isn’t in crisis — but it’s facing challenges that weren’t on anyone’s radar a generation ago.
Here’s what you can do:
- Check your water quality report. MLGW publishes an annual Consumer Confidence Report (CCR) that details what’s been detected in your water. You can find it on their website or request a copy.
- Know your neighborhood. If you live near industrial sites, former military installations, or areas with known contamination, consider having your water tested independently.
- Watch for PFAS updates. As federal PFAS regulations continue to evolve under the EPA’s PFAS Strategic Roadmap, Memphis utilities may need to add treatment for these compounds. Stay informed about what’s in your water.
If you’re concerned about your water quality, a certified water treatment professional can test your water and advise on solutions tailored to your specific situation.
Sources: U.S. Geological Survey — Memphis Sand Aquifer Studies, Memphis Light, Gas and Water, Tennessee Department of Environment and Conservation (TDEC), University of Memphis Center for Applied Earth Science and Engineering Research, EPA PFAS Strategic Roadmap