Wastewater Plants

Wastewater Treatment Plants treat an average of 12 million gallons of wastewater per day.

South Wastewater Treatment Plant


The South Wastewater Treatment Plant operates under a permit which has been established to control pollutant discharges. The permit is designed to regulate the manner, nature, volume and frequency for discharging from a particular source. The permit establishes specific limits on standards for discharging according to the rules and regulations of the State of Texas, orders of the Texas Commission on Environmental Quality and according to the Environmental Protection Agency. This permit also insures that the limits and standards established are met through proper enforcement such as annual plant inspections, bio-monitoring, and compliance monitoring.

The South Wastewater Treatment Plant has a design capacity of 10 Million Gallons per Day and is located on the South side of McAllen at 4100 Idela Ave. The South Wastewater Treatment Plant provides about 240 million gallons of reclaimed treated effluent yearly to the McAllen Palm View Golf Course for irrigation.


The State of Texas requires that all operators possess a valid certificate of competency issued by the Texas Commission on Environmental Quality. Any operator that operates a wastewater facility must be certified. There are four levels of competency for wastewater treatment plant operators, designated as A, B, C, and D. All applicants must pass an examination.


The sole purpose of the McAllen Public Utility South Wastewater Treatment Plant is to remove and properly dispose of pollutants that are harmful to aquatic life and to disinfect the wastewater before it is returned safely to the environment.

The McAllen South Wastewater Treatment Plant is an extended aeration plant which is an activated sludge process. Activated sludge is the sediment from the sewage that has been agitated in the presence of oxygen. This sediment of activated sludge contains living organisms that feed on sewage and require oxygen to live.

In this treatment system, the raw wastewater passes through an influent channel with a mechanical barscreen. The wastewater after bar screening then flows to the aerated grit chamber which removes gritty materials in the waste. After the grit chamber, the wastewater flows to the aeration basins.

The wastewater is then aerated in the aeration basins for biological stabilization. The mixture of the wastewater and sludge is agitated by mechanical surface aerators in the aeration basins.

The stabilized wastewater is then settled in the final clarifiers. A portion of the sludge from the clarifiers is digested in the aerobic sludge digester and a portion of the sludge is returned to the aeration basins to provide the necessary microorganisms in the aeration basins.

The clarified wastewater then flows to the chlorine contact chamber and disinfected with chlorine then dechlorinated with sulfur dioxide before being discharged into the Mission Floodway Channel.

The digested sludge from the aerobic digester is then dewatered in the belt filter press or the sludge drying beds.

The North Wastewater Treatment Plant


2100 W. Sprague McAllen, TX. 78504
Occupies 80 Acers of Land


In 1987 The North Wastewater Treatment Plant was constructed with the capacity of treating 4 Million Gallons per Day (MGD) Max Flow and subsequently Upgraded an additional 2 MGD in 1997 to treat 6 Million Gallons per Day (MGD) Max Treatment Capacity and again in 2005 was upgraded an additional (2 MGD) to a design capacity of 8 MGD Max treatment Capacity. In 2012 started a brand new Treatment Facility capable of treating 15 MGD Max Flow