The Trinity River—the main water source for the city of Houston, Texas—
provides one documented example of de facto water reuse, although it is by
no means a unique situation in the United States. Dallas and Fort Worth draw
water from the river’s headwaters and discharge their treated wastewater
downstream. During summertime and other times when the river’s natural flow
is reduced, the river consists almost entirely of treated wastewater as it flows
away from Dallas and Fort Worth.
After a two-week southward journey, during which natural processes
eliminate some trace organic contaminants, the water collects in Lake
Livingston—one of Houston’s main drinking water reservoirs. There it mixes
with rainwater and other water in the reservoir until it is drawn into a drinking
water treatment plant and distributed through Houston’s taps. Over the course
of a year, about half the lake’s water is made up of treated wastewater from
Dallas and Fort Worth. After treatment, the potable water from the Trinity
River meets Environmental Protection Agency drinking water standards.