El Paso draws its drinking water from three main sources: the Rio Grande, and two underground aquifer systems called the Hueco Bolson and the Mesilla Bolson. The river supplies nearly half of the city’s potable water, with groundwater from the two bolsons making up the rest. What makes El Paso’s water story unusual is how aggressively the city has invested in stretching those limited desert resources through desalination, aquifer recharge, and water recycling.
The Rio Grande
The Rio Grande is El Paso’s single largest water source, providing close to half of the city’s drinking water supply. Surface water from the river is treated at the Robertson/Umbenhauer Surface Water Treatment Plant before entering the distribution system. But the river is not a guaranteed resource. Allocations depend on snowpack in southern Colorado and northern New Mexico, upstream reservoir levels, and agreements with other users in both states and Mexico. In drought years, the city’s river allotment can drop significantly, forcing heavier reliance on groundwater.
The Hueco and Mesilla Bolsons
Beneath El Paso and the surrounding desert sit two large underground aquifer systems. The Hueco Bolson, on the east side of the Franklin Mountains, is the larger of the two, with rock and sediment layers reaching a maximum thickness of 9,000 feet. The Mesilla Bolson, to the west, extends to about 2,000 feet thick. Together they cover roughly 1,376 square miles and are shared with communities in southern New Mexico and Ciudad Juárez, Mexico.
Heavy municipal pumping through the mid-20th century caused water levels in the Hueco Bolson to drop by several hundred feet. By the late 1980s, the decline was serious enough to force a rethinking of how El Paso managed its groundwater. Since then, observation wells show that water levels have stabilized, largely because the city diversified its supply and began injecting treated water back into the aquifer.
The Kay Bailey Hutchison Desalination Plant
Some of the water in the Hueco Bolson is too salty for direct use. Rather than abandon that resource, El Paso built the Kay Bailey Hutchison Desalination Plant, which is the largest inland desalination facility in the United States. The plant has a design capacity of 27.5 million gallons per day. Of that, 15 million gallons is desalinated water (called permeate), and the remaining 12.5 million gallons is blended water that doesn’t require full desalination treatment. This plant allows the city to tap brackish groundwater that would otherwise be unusable, adding a meaningful cushion to the overall supply.
Aquifer Storage and Recovery
One of El Paso’s most innovative strategies is pumping highly treated wastewater back into the Hueco Bolson for future use. The system, known as aquifer storage and recovery (ASR), takes reclaimed wastewater from the Fred Hervey Water Reclamation Plant and injects it through a network of 10 recharge wells deep into the aquifer. Over roughly 18 years of operation, the system injected about 19.7 billion gallons of reclaimed water into the Hueco Bolson.
This serves two purposes at once. It replenishes groundwater that decades of pumping had depleted, and it puts treated wastewater to productive use instead of discharging it. The recovered water goes to municipal and industrial supply, golf course irrigation, power plant cooling, and construction. The program is a major reason the Hueco Bolson’s water levels stopped declining.
Direct Potable Reuse: The Next Step
El Paso is building what will be the first large-scale, direct-to-distribution potable reuse facility in the United States. The Advanced Water Purification Facility (AWPF) will take treated wastewater from the Bustamante Wastewater Treatment Plant, run it through advanced purification technologies, and send it directly into the city’s drinking water distribution system, skipping the step of storing it in an aquifer or reservoir first.
The facility is expected to produce 13,000 acre-feet of water per year with blending, enough to offset both growing demand and the increasing uncertainty of the Rio Grande supply. Construction is planned for completion by December 2026, with substantial completion by March 2027. For a desert city where the population continues to grow and climate change threatens snowpack-fed river flows, direct reuse represents a water source that doesn’t depend on rain, snowmelt, or ancient underground reserves.
Why El Paso’s Approach Matters
El Paso sits in the Chihuahuan Desert, receives about 9 inches of rain per year, and shares its water with two states and an international neighbor. Those constraints have forced the city to become one of the most water-resourceful in the country. Rather than depending on a single source, the system layers surface water, deep groundwater, desalinated brackish water, recycled wastewater, and soon direct potable reuse into a diversified portfolio. Each source backs up the others when drought, infrastructure problems, or allocation disputes reduce availability.
Per-capita water use in El Paso has dropped substantially over the past few decades, driven by conservation programs, tiered pricing, and desert-adapted landscaping requirements. The combination of lower demand and diversified supply has kept the city’s water situation stable even as the broader Southwest faces deepening shortages. It’s a model that other arid cities are increasingly studying as their own traditional sources come under pressure.