Summary of Washington's Water Reuse Guideline or Regulation for Environmental Restoration
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 for environmental restoration approved for use in Washington
- Water reuse treatment category for environmental restoration
- Additional context and definitions
- Water reuse for environmental restoration 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 reused for environmental restorationThe use of recycled water to create, sustain, or augment water bodies including wetlands, aquatic habitats, or stream flow. Includes groundwater or aquifer recharge for protection from saltwater intrusion , stream flow augmentation and wildlife habitat, and source water protection. include several specific definitions of wetlands. The source of water treated municipal wastewater Treated 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 below 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 wastewater for reuse applications related to environmental restoration for constructed wetlands both with and without public access. 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. Treatment requirements and performance standards are applied for the removal of microbial contaminants, chemicals and other relevant indicators for environmental restoration-related applications and are summarized in the table. The technical basis for developing the specifications and/or removals of microbial contaminants, chemicals and other relevant indicators is not explicitly specified.
Water reuse for environmental restoration approved for use in Washington
The use of reclaimed water is approved for release to:
- Category II wetlands without special characteristics, or with special characteristics on a case-by-case basis (Class A)
- Category III or IV wetlands (Class A)
- Constructed treatment or beneficial use wetlands with public access (Class A)
- Constructed treatment or beneficial use wetlands with no public access (Class B)
Water reuse treatment category for environmental restoration
In Washington, the various classes of reclaimed water treatment are defined by their respective treatment requirements and applicable performance standards.
- Class A treatment must meet Class B requirements (secondary treatment including biological oxidation and disinfection) and one of the following treatment process train requirements:
- 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.
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).
Washington uses four categories of wetlands, determined on a case-by-case basis with two separate rating systems (one for eastern Washington and one for western Washington). Special characteristics are also defined in each rating system. The four categories of wetlands are as follows (Hruby 2014a, 2014b):
- Category II wetlands are those that “are difficult, though not impossible to replace, and provide high levels of some functions.” In western Washington, Class II wetlands include smaller estuarine wetlands and interdunal wetlands larger than 1 acre or that are part of a mosaic. In eastern Washington, Class II wetlands include forest wetlands in the floodplains of rivers, mature and old-growth forested wetlands with fast growing trees and vernal pools. Special characteristics are also defined in each rating system.
- Category III wetlands are those with a moderate level of functions based on the rating system used in each region and can often be adequately replaced with a well-planned mitigation project. Many of these wetlands have been disturbed and are often less diverse or more isolated from other natural resources than Category II wetlands. In Western Washington, interdunal wetlands smaller than 1 acre are included in this category.
- Category IV wetlands are those with the lowest level of functions based on the rating system used in each region and are often heavily disturbed. These should be able to be replaced or possibly improved, but still warrant protection.
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 environmental restoration specifications
Summary of Washington's Water Reuse for Environmental Restoration 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 (Category II, III and IV wetlands; Constructed treatment or beneficial use wetlands with public access) |
Municipal wastewater |
Must meet the treatment requirements for Class B reclaimed water and any additional treatment criteria as specified in this table. |
||
|
5-day biochemical oxygen demand (BOD5)a |
20 mg/L (annual average) |
The parameter must be measured at the end of the unit process or alternative monitoring location as set in a reclaimed water permit. |
||
|
Total suspended solids (TSS)a |
20 mg/L (annual average) |
|||
|
Total Kjedahl Nitrogen (TKN)a |
3 mg/L (annual average) |
|||
|
Turbidity (coagulation and filtration) |
2 NTU (monthly average) 5 NTU (sample maximum) |
|||
|
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 mLb (sample maximum) |
|||
|
Virus removal |
Minimum 4-log virus removalc |
|||
|
Total nitrogen |
10 mg/L (monthly average) 15 mg/L (weekly average) |
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|
Phosphorusa |
1 mg/L |
|||
|
Annual hydraulic load (Category II wetlands without special characteristics)a |
2 cm/day |
|||
|
Annual hydraulic load (Category III-IV wetlands)a |
3 cm/day |
|||
|
Class B Reclaimed Water (Constructed treatment or beneficial use wetlands with no public 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) 45 mg/L (weekly average) |
|||
|
5-day carbonaceous biochemical oxygen demand (CBOD5) |
25 mg/L (monthly average) 40 mg/L (weekly average) |
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|
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 residuald |
≥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 Annual requirements apply unless it can be demonstrated that no existing significant wetland functions will be decreased and overall net environmental benefits will result from the release of reclaimed water.
b Listed as 23 MPN/mL or CFU/mL in Wash. Admin. Code § 173-219.
c Additional log reductions occur during drinking water treatment.
d If chlorine was used as the disinfectant.
Upcoming state law or policy
No upcoming environmental restoration reuse regulations were found for Washington.
References
Clean Water Act, 33 U.S.C. §§ 1251 et seq.
Reclaimed Water, Wash. Admin. Code § 173-219.
Reclaimed Water Use, Wash. Rev. Code 90-46.
Hruby, T. (2014a). Washington State Wetland Rating System for Eastern Washington: 2014 Update. (Publication #14-06-030). Olympia, WA: Washington Department of Ecology.
Hruby, T. (2014b). Washington State Wetland Rating System for Western Washington: 2014 Update. (Publication #14-06-029). Olympia, WA: Washington Department of Ecology.
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.