Summary of Washington's Water Reuse Guideline or Regulation for Industry
This page is part of the EPA’s REUSExplorer tool, which summarizes the different state level regulations or guidelines for water reuse for a variety of sources and end-uses.
The source water for this summary is Treated Municipal Wastewater.
On this page:
- Technical basis
- Water reuse industrial applications approved for use in Washington
- Water reuse treatment category for industrial applications
- Additional context and definitions
- Water reuse for industrial applications specifications (table)
- Upcoming state law or policy
- References
- Disclaimer
This page is a summary of the state’s water reuse law or policy and is provided for informational purposes only. Please always refer to the state for the most accurate and updated information.
In Washington, water reuse for industryThe use of recycled water for industrial applications, often created at the industrial facility. This includes recycled water generated through onsite processes such as boiler water, cooling water, manufacturing water, and oil and gas production, as well as recycled water generated offsite and imported elsewhere for industrial reuse applications. includes reuse for industrial uses indoors and with public contact, environmental contact and restricted access. The source of water treated municipal wastewaterTreated wastewater effluent discharged from a centralized wastewater treatment plant of any size. Other terms referring to this source of water include domestic wastewater, treated wastewater effluent, reclaimed water, and treated sewage. is specified by the state as municipal wastewater. The write-up on this page uses state terms when discussing sources or uses of water that may differ from the Regulations and End-Use Specifications Explorer’s (REUSExplorer’s) terms.
Technical basis
Washington approves the use of reclaimed water for industrial reuse applications that are indoors and that have public contact, environmental contact or restricted access (Wash. Admin. Code § 173-219). All applicable provisions of the Clean Water Act (CWA) (33 U.S.C. §§ 1251 et seq.), including its implementing regulations, must be met in addition to any state water quality standards. In Washington, no reclaimed water may be distributed or used without a state-issued reclaimed water permit (Wash. Admin. Code § 173-219; Wash. Rev. Code § 90-46). Treatment requirements and performance standards are applied for the removal of microbial contaminants, chemicals and other relevant indicators for industrial reuse applications and are summarized in the table. The standards for the specifications and/or removals of microbial contaminants, chemicals and other relevant indicators were developing utilizing references including the Ultraviolet Disinfection Guidelines for Drinking Water and Water Reuse (NWRI, 2012), Subpart H (Filtration and Disinfection) of the National Primary Drinking Water Regulations (40 C.F.R. § 141), numerous technical working group discussions throughout the rulemaking process and the public review and comment process (WA Ecology, personal communication, April 3, 2023).
Water reuse industrial applications approved for use in Washington
Wash. Admin. Code § 173-219 defines the following approved industrial reuse applications:
- Industrial uses indoors, e.g., non-contact cooling water, wash water and water used in making of non-food products like mixing concrete (Class A)
- Industrial uses with public contact (Class A)
- Industrial uses with environmental contact (Class B)
- Industrial uses with restricted access (Class B)
Water reuse treatment category for industrial applications
The various classes of reclaimed water treatment are defined by their respective treatment requirements and applicable performance standards. The respective treatment requirements are briefly summarized for industrial reuse applications:
- Class A treatment must meet Class B requirements (secondary treatment including biological oxidation and disinfection). Disinfection methods include chlorine, UV or other disinfection methods that are in accordance with the most recent Criteria for Sewage Works Design (WA DOE, 2019). Additionally, one of the following treatment process train requirements must be met:
- Biological oxidation, followed by coagulation, filtration and disinfection, demonstrating at least a 4-log virus removal or inactivation.
- Biological oxidation, followed by membrane filtration and disinfection, demonstrating at least a 4-log virus removal or inactivation.
- Combination of biological oxidation and membrane filtration via a membrane bioreactor, followed by disinfection, demonstrating at least a 4-log virus removal or inactivation.
- An alternative treatment method, that demonstrates to the satisfaction of the lead agency that it provides for equivalent treatment and reliability.
- For Class B water, the treatment requirements are secondary treatment, including biological oxidation, followed by disinfection. Disinfection methods include chlorine, UV or other disinfection methods that are in accordance with the most recent Criteria for Sewage Works Design (WA Ecology, 2022).
Additional context and definitions
Washington defines reclaimed water as “water derived in any part from a wastewater with a domestic wastewater component that has been adequately and reliably treated to meet the requirements of this chapter, so that it can be used for beneficial purposes” (Wash. Admin. Code § 173-219). Industrial uses are defined as “non-potable uses of water to produce products, provide goods and services” (Wash. Admin. Code § 173-219). The term does not include land application or irrigation uses” (Wash. Admin. Code § 173-219).
Industrial reuse water is defined as water “that has been used for the purpose of industrial processing and has been adequately and reliably treated so that, as a result of that treatment, it is suitable for other uses” (Wash. Rev. Code § 90-46).
Class A and B municipal reclaimed water piping, valves, outlets, storage facilities and other appurtenances must be color-coded purple and the pipes must be at least 200 feet away from potable water intakes, including well-heads, springs, surface water or designated groundwater (Wash. Admin. Code § 173-219). The reclaimed water generator must notify the public and employees at the site of the reclaimed water (for all use areas) by posting advisory signs or distributing advisory notices. The signage must be purple-colored and read “Reclaimed Water – Do Not Drink”.
Water reuse for industrial applications specifications
Summary of Washington's Water Reuse for Industrial Applications Reuse Specifications
| Recycled Water Class/Category | Source Water Type | Water Quality Parameter | Specification | Sampling/Monitoring Requirements (Frequency of monitoring; site/ location of sample; quantification methods)* |
|---|---|---|---|---|
|
Class A Reclaimed Water (Industrial uses with public contact) |
Municipal wastewater |
Must meet the treatment requirements for Class B reclaimed water and any additional treatment criteria as specified. |
||
|
Turbidity (coagulation/filtration) |
2 NTU (monthly average) |
The parameter must be measured at the end of the unit process or alternative monitoring location as set in a reclaimed water permit. | ||
| Turbidity (membrane filtration) | 0.2 NTU (monthly average) 0.5 NTU (sample maximum) |
|||
| Total coliform | 2.2 MPN/100 mL or CFU/100 mL (7-day median) 23 MPN/100 mL or CFU/100 mLa (sample maximum) |
|||
| Virus removal | Minimum 4-log virus removalb | |||
| Chlorine residualc | ≥1 mg/L | After a contact time of at least 30 minutes based on peak day design flow | ||
|
Class B Reclaimed Water (Industrial uses with environmental contact and restricted access) |
Municipal wastewater |
Dissolved oxygen |
Must be measurably present |
The parameter must be measured at the end of the unit process or alternative monitoring location as set in a reclaimed water permit. |
|
5-day biochemical oxygen demand (BOD5) |
30 mg/L (monthly average) |
|||
| 5-day carbonaceous biochemical oxygen demand (CBOD5) | 25 mg/L (monthly average) 40 mg/L (weekly average) |
|||
| Total suspended solids (TSS) | 30 mg/L (monthly average) 45 mg/L (weekly average) |
|||
| pH | 6–9 | |||
| Total coliform | 23 MPN/mL or CFU/mL (7-day median) 240 MPN/mL or CFU/mL (sample maximum) |
|||
| Chlorine residualc | ≥1 mg/L | After a contact time of at least 30 minutes based on peak day design flow | ||
Source= Wash. Admin. Code § 173-219
* Information about sampling and monitoring requirements such as frequency, site and quantification methods not specifically listed in the table was not explicitly specified in the state-specific regulations.
a Listed as 23 MPN/mL or CFU/mL in Wash. Admin. Code § 173-219.
b Additional log reductions occur during drinking water treatment.
c If chlorine was used as the disinfectant.
Upcoming state law or policy
No upcoming regulations related to industrial water reuse were found for Washington.
References:
Clean Water Act, 33 U.S.C. §§ 1251 et seq.
National Primary Drinking Water Regulations, 40 C.F.R. § 141.
National Water Research Institute (NWRI). 2012. Ultraviolet Disinfection Guidelines for Drinking Water and Water Reuse, Third Edition.
Reclaimed Water, Wash. Admin. Code § 173-219.
Reclaimed Water Use, Wash. Rev. Code § 90-46.
State of Washington Department of Ecology (WA Ecology). 2022. Criteria for Sewage Works Design (Orange Book).
Please contact us at [email protected] if the information on this page needs updating or if this state is updating or planning to update its laws and policies and we have not included that information on the news page.