Regulations Governing the Use of
Reclaimed Water for Cooling Purposes


The operation of a water reuse program must be within the framework of federal and state regulations and these must be addressed in the earliest planning stages. These regulations are,

Federal Regulations

Water Reuse Regulations
Water Discharge Regulations
Air Emission Regulations
Interbasin Water Transfer Regulations

State Regulations


Part of the Shearon Harris nuclear power plant near Raleigh, N.C.
(Progress Energy, Murray & Associates)



  • Federal Regulations:

Currently, there are no federal regulations directly related to the practices of water reuse in the U.S., including no specific federal regulations governing the reuse of reclaimed water as power plant cooling water. Many states, however, do have regulations pertaining to water reuse. At the federal level, the U.S. Environmental Protection Agency published “Guidelines for Water Reuse” for the benefit of utilities and regulatory agencies (USEPA, 2004). “Guidelines for Water Reuse” provides an overview of (1) types of reuse applications, (2) related technical issues, (3) water-reuse regulations/guidelines established by each state, (4) legal and institutional issues, (5) funding water reuse systems, (6) public involvement programs, and (7) water reuse in other countries. For those states having no water reuse regulations/guidelines, the USEPA guideline document provides suggestions about treatment, reclaimed water quality, reclaimed water monitoring, and minimal distance between wastewater source and public area.



  • Water Reuse Regulations:

“Guidelines for Water Reuse” suggests treatment and desired reclaimed water quality for water reuse in industrial cooling systems, including once-through cooling and re-circulating cooling towers. The reclaimed water quality for industrial reuse suggested by the USEPA is summarized in Table 1. Since the general focus of reclaimed water use is on municipal wastewater, suggested standards for cooling towers are correlated to the municipal wastewater discharge standards. Any effluent leaving the wastewater treatment plant is regulated by technology-based limits on BOD5, TSS, and pH.

Federal regulations do not govern how the power plant uses reclaimed water inside their facility. Therefore, the water quality requirements are established by the local government based on the operational requirements.

Table 1. Summary of reclaimed water quality when used in cooling water system (USEPA, 2004)

System Treatment pH BOD5 TSS Fecal
30 mg/l
30 mg/l

d daily)


1 mg/l
Re- continuous)
and filtration
may be
depends on



  • Water Discharge Regulations

    Clean Water Act governs all discharges of pollutants into the surface water. Cooling tower is regulated and referred to as a point source. While there are no federal regulations focused specifically on the effluent discharge of reclaimed water from industrial cooling systems, Section 402 of the Clean Water Act requires that all point source discharges of pollutants to surface waters must be authorized by National Pollutant Discharge Elimination System (NPDES) discharge permits. Limits in NPDES permits can be technology-based or water-quality-related. Specific Clean Water Act regulations in the Code of Federal Regulations (40CFR423) provide effluent standards for steam electric power generating plant discharges, categorized as:

    1. The best practicable control technology currently available (BPT);
    2. The best available technology economically achievable (BAT);
    3. New source performance standards (NSPS);
    4. Pretreatment standards for existing sources (PSES); and
    5. Pretreatment standards for new sources (PSNS).

    As noted by the California Energy Commission (2003), the only aspect of BPT that applies to any current or future power plant discharges is pH limits of 6.0~9.0. Other BPT controls are superseded by BAT. A summary of effluent standards from 40CFR423 is shown in Table 2.

    Table 2. Summary of 40CFR423 related to BPT, BAT, NSPS, PSNS, and PSES in once through cooling water and cooling tower blowdown.

      pH Free available Chlorine Total Chromium Total Zinc
        One day
days) (mg/l)
One day
days) (mg/l)
One day
days) (mg/l)
BPT   0.5 0.2        
BAT/NSPS >25MW   0.2          
  <25MW   0.5 0.2        
BPT 6~9 0.5 0.2        
BAT, NSPS 6~9 0.5 0.2 0.2 0.2 1.0 1.0
PSNS       0.2   1.0  
PSES       0.2   1.0  

1) For BAT, NSPS, PSNS, and PSES, the 126 priority pollutants (except chromium and zinc) contained in chemicals added for cooling tower maintenance should be in non-detectable amounts.
2) The 126 priority pollutants are listed in Appendix A to 40CFR423



  • Air Emission Regulations

Evaporative condensation of water occurs when the warm water gets in contact with air in wet re-circulating cooling towers. Millions of small droplets, also called “drift”, are exhausted with air into the atmosphere from these towers. The “Guidelines for Water Reuse” recommended that when reclaimed water is used in industrial cooling, windblown spray should not reach areas accessible to workers or the public. The drift usually contains highly concentrated elements, including metals, nutrients, and microorganisms, which may increase the health risk for residents in the vicinity of the
power plant. Cooling tower drift can contain all the chemicals present in the recirculating cooling water (USEPA, 2004).

The federal government does not offer specific limitations on air emission from industrial cooling systems using reclaimed water for cooling purposes. Nonetheless, there are regulations related to air emissions from cooling towers. According to USEPA (2005), cooling towers are categorized as potential point emission sources of volatile organic compounds (VOC), PM10, PM2.5, and NH3. USEPA (1995) provides a compilation of emission factors for these air pollutants for estimation purposes, but the values listed are neither EPA-recommended emission limits (e.g., best available control technology or
BACT, or lowest achievable emission rate or LAER) nor standards (e.g., National Emission Standard for Hazardous Air Pollutants or NESHAP, or New Source
Performance Standards or NSPS).

Particulate Emission Regulations Pertinent to Cooling Towers in the United States:

Particulate matter emissions from cooling towers are a concern primarily because they are aerosols that may be easily inhaled and deposited into the respiratory system. Drift eliminators are able to reduce the amount of cooling water lost as a drift to a range between 0.0005-0.002% of the total recirculation flow rate. However, most of the loss is as PM10 which is the particle size of highest concern. Regulations pertaining to
cooling towers are similar to those in place for vehicles and power plants and therefore are set in terms of particle mass per airflow volume (μg/m3). National ambient air quality standards (NAAQS) set particulate matter criterion, whereas each state regulates the amount of water used for cooling purposes. If the total dissolved solids in the cooling water are established, total particulate emissions can be estimated using the drift loss. If
there are no data for total dissolved solids in the cooling water, particulate emissions can be estimated using PM10 emission factor (EPA,1995) resulting in total drift to PM10 ration of 89.5:1.

National Ambient Air Quality Standards (NAAQS):

Particulate matter regulations were issued together with six criteria pollutants in 1971 and then revised in 1997 (USEPA, 2009). In 1990, the Clean Air Act required EPA to set up standards for all pollutants that are considered harmful to public health and the environment, which are known as National Ambient Air Quality Standards (40 CFR part 50).

The specific standard for total particulate matter was introduced in 1987 by NAAQS, with maximum concentration in a 24-hour period of 150 μg/m3 and annual average of 50 μg/m3. This standard was later referred as PM10. In 1997, EPA established new NAAQS for PM, which included standards for particles smaller than 2.5 μm (PM2.5) and smaller than 10 μm (PM10) (EPA, 1997). The PM criteria are listed in Table 3.

Table 3. Particulate Matter Criteria issued in NAAQS

Pollutant Primary
Averaging Times Secondary
Particulate Matter
Revoked* Annual (Arith. Mean)  
150 μg/m3 24-hour  
Particulate Matter
15.0 μg/m3 Annual (Arith. Mean) Same as Primary
35 μg/m3 24-hour  

Note: *Due to a lack of evidence linking health problems to long-term exposure to coarse particle pollution, the agency revoked the annual PM10 standard in 2006 (effective December 17, 2006)
Source: National Ambient Air Quality Standards, USEPA, 2006



  • Interbasin Water Transfer Regulations:

Existing federal laws are not directly governing interbasin water transfer, but some environmental laws can influence interbasin water transfer. Table 4 shows that several laws, including the National Environmental Policy Act (NEPA), the Clean Water Act (CWA), and the Endangered Species Act (ESA), indirectly relate to interbasin water transfer. The major concern is mainly about the potential impacts on environment caused by transporting water from one basin to another. As stated in the CWA, interbasin transfers are usually governed by states except in special cases such as Great Lakes and federally authorized reclamation projects which involve interstate impacts (Craig, 2007).

Table 4. Federal environmental laws that indirectly affect interbasin water transfer.

Law Description
The National Environmental Policy Act (NEPA) Federal agencies are required to assess potential environmental impacts of proposed “major federal actions”. The agencies must hold hearings that allow public participation and then prepare an “environmental impact statement” document.
The Clean Water Act (CWA) Although the Clean Water Act does not regulate interbasin water transfer, the depletion of a stream used by the transfer of water to other basin can adversely impact water quality. Section 404 of the CWA requires the U.S. Army Corps of Engineers to review the impacts and
require mitigation for the impacts of a water development on the basin of origin.
The Endangered Species Act (ESA) The ESA prohibits any action that would jeopardize the existence of an endangered species.




  • State Regulations

As summarized in “Guidelines of Water Reuse” (USEPA, 2004), most states have established regulations and/or guidelines on water reuse for different purposes. Among those states, California, Florida, Hawaii, New Jersey, North Carolina, Oregon, Texas, Utah, and Washington have regulations and guidelines for industrial reuse of reclaimed water. The regulations/guidelines for reclaimed water use in industrial cooling water systems in these ten states are reviewed here

Table 5. Summary of water reuse regulations and guidelines by states*.















Alabama   O     O   O            
Alaska O           O            
Arizona O     O O O O   O        
Arkansas   O   O O O O            
California(3) O     O O O O O O   O O O
Colorado O     O O O O O O        
Connecticut     O                    
Delaware O     O O   O            
Florida O     O O O O     O O O O
Georgia   O   O O   O            
Hawaii   O   O O O O   O   O O O
Idaho O     O O O O            
Illinois O     O O   O            
Indiana O     O O O O            
Iowa O       O   O            
Kansas   O   O O O O            
Kentucky     O                    
Louisiana     O                    
Maine     O                    
Maryland   O     O   O            
Massachusetts   O   O O   O         O O
Michigan O         O O            
Minnesota     O                    
Mississippi     O                    
Missouri O       O   O            
Montana O     O O O O            
Nebraska O       O   O            
Nevada O     O O O O O O        
New Hampshire     O                    
New Jersey   O   O O O O       O    
New Mexico   O   O O O O            
New York   O     O   O            
North Carolina O     O             O    
North Dakota   O   O O   O            
Ohio   O   O O   O            
Oklahoma O       O O O            
Oregon O     O O O O O O   O    
Pennsylvania   O     O   O            
Rhode Island     O                    
South Carolina O     O O   O            
South Dakota   O   O O   O            
Tennessee O     O O   O            
Texas O     O O O O O O   O    
Utah O     O O O O O O   O    
Vermont O           O            
Virginia     O                    
Washington   O   O O O O O O O O O O
West Virginia O       O O O            
Wisconsin O       O   O            
Wyoming O     O O O O            

*Adapted from “Guidelines of Water Reuse”, USEPA, 2004.
**States reviewed in this study are those that are shaded in this table.


Table 6. Summary of regulations and guidelines reviewed in the twelve selected states.


Water Reuse Regulations

Water Discharge Regulations

Air Emission


*AAC, R18-9, Article 7

• AAC, R18-9 Article 9



* State Water Resources Control Board, Resolution No.75-58
* Warren-Alquist Act, Section
* Water Code, Section 462
* 22CCR60306

* State Water
Resources Control
Board, Resolution
No. 75-58

* 22CCR60306
• 17CCR93103


* FAC 62-610-668

• FAC 62-302-520
• FAC 62-660.400

* FAC 62-610-668


* Guidelines for the
Treatment and Use of
Recycled Water, III, C
(Dep. of Health, 2002)


* Guidelines for the Treatment and Use of Recycled Water, III, C (Dep. of Health, 2002)



• COMAR26.08.03.06


New Jersey

* Reclaimed Water for
Beneficial Reuse (Dep. of
Env. Pro., 2005)



North Carolina

* 15A NCAC 02T.0906
* 15A NCAC 02T.0910

• 15A NCAC 02B.0208
• 15A NCAC 02B.0211
• Thermal
Variances to North
Carolina Water
Quality Standards
(USEPA, 2006)



* OAR 340-550-0012


* OAR 340-550-0012


* TAC 30-210.32
* TAC 30-210.33

• TAC 30-307.8

* TAC 30-210.32
* TAC 30-210.33
• TAC 30-113.220


* Water Reuse in Utah
(Division of Water
Resource, 2005)
* UAC R317-3-11
* RCW 90.46


* UAC R317-3-11


* Water Reclamation of
Reuse Standards (Dep. of
Health & Dep. of Ecology,


* Water Reclamation of
Reuse Standards (Dep. of Health & Dep. of Ecology, 1997)


• WQRS Chapter 21

• WQRS Chapter 2


* Related to reuse of reclaimed water in power plant cooling water system.
• Related to power plant cooling water system.