Summary of Idaho's Water Reuse Guideline or Regulation for Centralized Non-potable Reuse
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
- Applications of centralized non-potable reuse approved for use in Idaho
- Water reuse category/type
- Additional context and definitions
- Centralized non-potable reuse 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 Idaho, centralized non-potable reuse The use of recycled water for centralized non-potable reuse where the water does not derive from the same site where it is to be reused. Can include, but is not limited to, toilet flushing, dust control, soil compaction, fire protection, commercial laundries, vehicle washing, street cleaning, snowmaking, and other similar uses. Excludes on-site non-potable water reuse and the use of recycled water for agriculture or landscaping. applications include snowmaking, commercial laundries, firefighting and cleaning roads, among others. 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
Idaho approves the reuse of recycled water for centralized non-potable applications including, but not limited to, commercial laundries, snowmaking, firefighting, street cleaning, soil compaction and dust control (Idaho Admin. Code r. 58.01.17). 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. The classes of recycled water treatment differ by the level of pathogen and chemical removal and treatment requirements (see the table below for more information). Idaho Department of Environmental Quality uses California’s Title 22 Water Recycling Criteria (Cal. Code Regs. tit. 22) as the technical basis for the derivation of total coliform removals and turbidity requirements (defined in the table below).
Applications of centralized non-potable reuse approved for use in Idaho
Idaho Admin. Code r. 58.01.17 defines the following approved centralized non-potable reuse applications:
- Snowmaking for winter parks, resorts (Class A)
- Commercial laundries (Class A)
- Firefighting
- Fire suppression (Class B)
- Nonstructural firefighting (including but not limited to wildfires) (Class C)
- Toilet flushing at industrial and commercial sites when only trained maintenance personnel have access to plumbing for repairs (Class C)
- Cleaning roads, sidewalks and outdoor work areas (Class C)
- Soil compaction (Class C)
- Dust suppression at construction sites and dust control on roads and streets (Class C)
Idaho approves the use of recycled water (of all recycled water class types) for other commercial and non-potable reuse applications on a case-by-case basis. Other uses not listed here may be considered on a case-by case basis and approved by the Idaho Department of Environmental Quality and would be specified in a reuse permit. For example, a commercial carwash facility has been a use approved for Class A recycled water.
Water reuse category/type
The various classes of treatment are defined by their respective treatment requirements and applicable performance standards. The respective treatment requirements are briefly summarized below for centralized non-potable reuse applications.
- For Class A recycled water, municipal wastewater is required to be “oxidized, coagulated, clarified, and filtered, or treated by an equivalent process and adequately disinfected” (Idaho Admin. Code r. 58.01.17.601). Class A recycled water must be disinfected by either:
- A chlorine disinfection process that meets the requirements for Class A water in the table below; or
- A disinfection process that, when combined with filtration, has been demonstrated to achieve 5-log inactivation of virus. “Acceptance by the State of California as published in their Treatment Technology Report for Recycled Water is one method to constitute such a demonstration. (7-1-21)” (Idaho Admin. Code r. 58.01.17.601). Disinfection methods are considered on a case-by-case basis.
- For Class B recycled water, municipal wastewater is required to be “oxidized, coagulated, clarified, and filtered, or treated by an equivalent process and adequately disinfected” (Idaho Admin. Code r. 58.01.17.601). Class B treatment systems must be reviewed by the Department of Environmental Quality and approved on a case-by-case basis. Pilot testing or demonstration might be required prior to approval or may condition approval upon the successful outcome of such testing or demonstration. Class B recycled water must be disinfected by either:
- A chlorine disinfection process that meets the requirements for Class B in the table below; or
- An alternative disinfection process that has been demonstrated to the satisfaction of the Department of Environmental Quality to be comparable to that achieved by chlorination with a total chlorine residual of 1 mg/L after a minimum contact time of 30 minutes.
- For Class C recycled water, municipal wastewater is required to be oxidized and adequately disinfected to meet the total coliform requirements for Class C recycled water in the table below (Idaho Admin. Code r. 58.01.17.601).
Additional context and definitions
Idaho defines recycled water as “water that has been treated by a wastewater treatment system and is used in accordance with the rules” in Idaho Admin. Code r. 58.01.17.
Idaho requires that all new buried pipe, exposed and above ground pipe conveying Class A municipal recycled water must be colored purple. For Class A, B and C municipal recycled water, signs must be posted at the area of use that state “Caution: Recycled Water - Do Not Drink” in both English and Spanish (Idaho Admin. Code r. 58.01.17).
Centralized non-potable reuse specifications
Summary of Idaho's Centralized Non-potable 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 (snowmaking for winter parks/resorts, commercial laundries) |
Municipal wastewater |
Total coliform |
≤2.2 MPN/100 mL (7-day median) ≤23 MPN/100 mL (single sample maximum) |
Daily, or at a lower frequency determined based upon, but not limited to, the following: uses that are allowed with lower class recycled water, the volume of recycled water used, the disinfection method used, the demonstrated disinfection efficiency and reliability, the point of compliance or other factors demonstrating that the alternative frequency is protective of public health. |
|
Turbidity (granular or cloth media filtration) |
2 NTU (24-hour mean) 5 NTU (single sample maximum) |
Continuous monitoring |
||
|
Turbidity (membrane filtration) |
0.2 NTU (24-hour mean) 0.5 NTU (single sample maximum) |
|||
|
Total nitrogen |
≤30 mg/L |
Not specified |
||
|
5-day biochemical oxygen demand (BOD5) |
≤10 mg/L (monthly mean) |
Weekly composite samples |
||
|
pH |
6.0–9.0 |
Daily grab samples or continuous monitoring |
||
|
Disinfection requirements contact time |
450 mg-min/L with 90 min of modal time, or Disinfection to 5-log inactivation of virus |
Dependent upon method used, demonstrated disinfection efficiency and reliability, point of compliance or other factors |
||
|
Class B (fire suppression) |
Municipal wastewater |
Total coliform |
≤2.2 MPN/100 mL (7-day median) ≤23 MPN/100 mL (single sample maximum) |
Daily, or as determined |
|
Turbidity (granular or cloth media filtration) |
5 NTU (24-hour mean) 10 NTU (single sample maximum) |
Continuous monitoring |
||
|
Disinfection requirements contact time |
Total chlorine ≥1 mg/L after 30 min contact time at peak flow, or alternate comparable process |
Dependent upon method used, demonstrated disinfection efficiency and reliability, point of compliance or other factors |
||
|
Class C (nonstructural firefighting, toilet flushing at commercial and industrial sites, road/sidewalk cleaning, soil compaction, dust suppression) |
Municipal wastewater |
Total coliform |
≤23 MPN/100 mL (5 -day median) ≤230 MPN/100 mL (single sample maximum) |
Once weekly or at a lower frequency based upon, but not limited to, the following: uses that are allowed with lower class recycled water, the volume of recycled water used, the disinfection method used, the demonstrated disinfection efficiency and reliability, the point of compliance or other factors demonstrating that the alternative frequency is protective of public health. The point of compliance for Class C recycled water for total coliform shall be at any point in the system following final treatment and disinfection contact time. |
Source = Idaho Admin. Code r. 58.01.17
* 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.
Upcoming state law or policy
No upcoming regulations pertaining to centralized non-potable reuse were found for Idaho.
References:
Clean Water Act, 33 U.S.C. §§ 1251 et seq.
Recycled Water Rules, Idaho Admin. Code r. 58.01.17.
Water Recycling Criteria, Cal. Code Regs. tit. 22.
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.