United Water
Bexar Metropolitan Water District
San Antonio, Texas
In San Antonio, the difference between good water and great water is
0.01 micrometers—ten thousand times smaller than a human hair. That’s the
width of the pores in an ultrafiltration system designed, built and operated by
United Water in San Antonio’s Bexar Metropolitan Water District.
The ultra filtration plant treats water from the Medina River, making it the first facility in the San Antonio area to treat surface water. The system, the largest of its kind in the United States, went into operation in early 2000. This represented a major step in easing water demand on the Edwards Aquifer. In all, nearly 3.56 billion gallons of water are saved each year. Better still, United Water has since found it can safely boost the plant’s 9 million gallons per day (mgd) design capacity to 14.5-mgd in the summer and reduce it to 10.8-mgd in winter.
United Water achieved this without additional capital investment. The high-tech water treatment plant is part
of a 10-year, $30 million agreement between United Water and the Bexar Metropolitan Development
Corporation (BMDC), an industrial development corporation formed by the water district. Under the terms of the contract,
United Water is responsible for all aspects of designing, building, managing, and operating the new surface water facilities. For its part, the BMDC owns the facilities, provided financing for the project, and constructed a five-mile pipeline and the
storage facility.
At the San Antonio facility, surface water is obtained from the Medina and during the second phase of the treatment process, water is pumped to the ultra filtration racks. Each of the 5.4 million thin, plastic membranes acts like a strainer, holding back unwanted particles and contaminants, but allowing water, minerals and small molecules to pass through. Together, the membranes can produce more than 10,000 gallons of crystal clear water per minute. One benefit of the water ultra filtration treatment process is that it is highly efficient in removing bacteria and microorganisms. As a result, ultra-pure water contains fewer particles and requires less chlorine disinfection than water treated by
other methods.
It is then distributed to customers in southern San Antonio and other parts of the city. All of this has been accomplished using a procurement methodology that reduced the total cost of the project to $1.214 per
1,000 gallons produced—an estimated 30 percent reduction over traditional approaches.
United Water provides water and wastewater services to 7 million people in the
United States. In addition to owning and operating regulated utilities, United Water operates municipal systems through public-private partnerships and contact agreements. |
