What is a publicly owned treatment works (POTW)?
Key Highlights
- Publicly Owned Treatment Works (POTWs) are defined in 40 CFR §403.3 (General Pretreatment regulations for Existing and New Sources of Pollution) (q).
- The discharges in POTWs are regulated by the EPA.
- The National Pretreatment Program provides the regulatory framework for nondomestic dischargers to ensure compliance with the Clean Water Act.
- Water treatment and wastewater treatment differ in the source of their incoming water although both employ similar processes.
- There is a trend in the privatization of wastewater treatment facilities due to the increasing cost of repairing aging infrastructure of the wastewater treatment plants and for their operations.
Publicly Owned Treatment Works (POTWs) are wastewater treatment facilities for treating domestic sewage and industrial wastewater to remove harmful chemicals and pathogens. POTWs collect wastewater (which is raw sewage) from homes, commercial buildings, and industrial facilities and then transport it via a collection system which is basically a series of pipes to the treatment plant. At the treatment plant, chemicals and harmful microorganisms are removed from the water before it is discharged into the receiving stream.
Regulation for discharges into the POTWs are set by U.S. EPA and these regulations also include The National Pretreatment Program with the aim to reduce the discharge of harmful pollutants that could interfere with the operations in a POTW. With more than 14,000 POTWs in the United States, there is a trend in the privatization of wastewater treatment facilities to meet the high costs associated with repairing aging infrastructure of the wastewater treatment plants and their operational costs.
Legal definition of POTW
The term POTW is defined in 40 CFR §403.3 (General Pretreatment regulations for Existing and New Sources of Pollution) (q) as follows:
Publicly Owned Treatment Works or POTW means a treatment works as defined by Section 212 of the Clean Water Act, which is owned by a state or municipality (as defined by Section 502(4) of the Clean Water Act). This definition includes any devices and systems used in the storage, treatment, recycling and reclamation of municipal sewage or industrial wastes of a liquid nature. It also includes sewers, pipes, and other conveyances only if they convey wastewater to a POTW. The term also means the municipality as defined in Section 502(4) of the Clean Water Act, which has jurisdiction over the Indirect Discharges to and the discharges from such a wastewater treatment plant.
What is a POTW in the EPA?
A POTW in the EPA refers to regulations and monitoring of the POTW done by the EPA. The EPA sets regulations for POTWs, ensuring compliance within the legal regulatory framework. The EPA also collects data about industrial discharges into POTWs. For example as part of the commitment in October 2021 PFAS Strategic Roadmap, the EPA collected data about the industrial discharge of perfluorooctanoic acid (PFOA) into POTWs and made this data publicly accessible. POTWs do not produce PFOA but receive wastewater containing PFOA.
Who regulates POTWs?
The EPA sets regulations for discharges into POTWs and as such, the EPA regulates POTWs. These regulations include:
- Pretreatment standards which are pollutant discharge limits and these could be substantive or procedural requirements. They include general prohibitions as set in 40 CFR Part 403.5(a) that forbids the discharge of any pollutants to a POTW that can cause pass through or interfere with the POTW, with its treatment processes, sludge processes, or disposal.
- Specific prohibitions as set in 40 CFR Part 403.5(b) that are intended to “enhance the control of hazardous wastes entering POTWs” as set in 55 FR 30082.
What is pretreatment?
Pretreatment is a nationwide program consisting of treatment techniques and management practices to reduce or eliminate the discharge of harmful pollutants and contaminants that could interfere with or pass through the biological processes in a POTW. Pretreatment is done before the wastewater enters the POTW.
The National Pretreatment Program
Pretreatment is legally known as The National Pretreatment Program published in 40 CFR Part 403. It provides the regulatory framework for nondomestic dischargers to ensure compliance with the goals of the Clean Water Act. The objectives of The National Pretreatment Program is to prevent the introduction of pollutants into POTWs that will interfere with the operation of a POTW, that will pass through the treatment, and that will interfere with the safety of the disposed municipal sludge. A second objective is to provide resources for recycling and reclaiming municipal and industrial wastewater and sludges.
What is the difference between water treatment and wastewater treatment?
In the water treatment world, there is a difference between water treatment and wastewater treatment. Both are treated at facilities called treatment plants. However, both treat water originating from different sources.
Overview of the difference
According to the Pennsylvania Water Environment Association, a water treatment plant generally takes water from the ground, surface, or rainwater sources and treats it to make it drinkable. It is then distributed to storage tanks or distributed directly to people.
A wastewater treatment plant, by comparison, collects water coming in as waste from homes (called sewage) and in some cases as stormwater. It is treated at the wastewater treatment plant and is then released to a nearby waterway. This release is called discharge, and carries regulatory and compliance requirements be met before the water is discharged to a waterway.
In general, water treatment treats water from natural sources whereas wastewater treatment treats sewage and storm water.
Comparison of treatment processes
Water treatment includes coagulation, flocculation, sedimentation, filtration, and disinfection. These processes also occur in wastewater treatment in the different treatment levels, namely primary, secondary, and tertiary treatments. Sedimentation along with screening via filtration, coagulation, flocculation, and grit removal are steps in the primary treatment. In the secondary treatment, biological processes occur to remove soluble organic matters and suspended solids. Persistent pollutants such as nutrients and pathogens that still remain in the water are removed in the tertiary treatment using disinfection.
How many POTWs are in the United States?
Published sources give different numbers for how many POTWs there are in the United States. For example:
- The 2022 Clean Watersheds Needs Survey report stated there are 17,544 POTWs in the United States.
- As of March 2024, the EPA estimates there are approximately 14,700 POTWs in the United States.
- FEMA reported there are over 16,000 POTWs in the United States.
Based on these numbers, it can be said that there are more than 14,000 POTWs in the United States.
Who owns wastewater plants?
According to the definition of POTW in 40 CFR §403.3 (General Pretreatment regulations for Existing and New Sources of Pollution) (q), a POTW is owned by a state or municipality. Typically, a POTW is owned and operated by a government agency.
However in recent years as published sources point out, there is a trend in the privatization of wastewater treatment facilities due to aging infrastructure of wastewater treatment facilities in need of costly repairs, funding cuts driven in part to reduce taxes, increase in population leading to an increase in the amount of wastewater coming into the treatment plants, and the need to adopt newer cost-effective technologies for wastewater treatment.
How many people work at a wastewater treatment plant?
The number of people who work at a wastewater treatment plant varies depending on the size of the wastewater treatment plant and locations among other factors. The following are some examples of the data from published sources:
- Statista: In 2019, there were 199,900 people working in the wastewater treatment industry.
- Data USA: In 2023, there were 106,000 water and wastewater treatment plant and system operators.
Notably according to information on the website for the U.S. Bureau of Labor Statistics, the employment of water and wastewater treatment plant and system operators is projected to decline by 7% from 2024 to 2034. The website further says that despite declining employment, about 10,700 openings for water and wastewater treatment plant and system operators are projected each year on average over the decade expected due to the need to replace workers who transfer into other occupations or exit the labor force due to retirement.
About the Author
Saleha Kuzniewski
Saleha Kuzniewski, Ph.D. has authored several publications in the fields of scientific research, biotechnology, and environmental regulations. She is the winner of the 2023 Apex award for publication excellence. She is also the founder of Environmental Remediation & Innovations, LLC. Kuzniewski can be reached at [email protected].