Summary of Idaho's Water Reuse Guideline or Regulation for Landscaping
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 landscaping approved for use in Idaho
- Water reuse treatment category for landscaping
- Additional context and definitions
- Water reuse for landscaping 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, water reuse for water reuse for landscapingThe use of recycled water on land to assist in the irrigation of vegetation in residential and non-residential areas. Includes impoundments to store water for irrigation , ornamental vegetation, parks, school yards, sporting facilities (including golf courses), private gardens, roadsides and greenbelts, and cemeteries. Excludes irrigation of areas used for agriculture, commercial reuse applications, or any centralized non-potable reuse. includes parks, playgrounds and school yards during periods of use; residential landscapes; parks, playgrounds and school yards during periods of non-use; golf courses; highway medians and roadside vegetation on sides; and cemeteries. 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 . This write-up 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 landscaping irrigation, including irrigation of residential landscapes, cemeteries and highway areas as well as playgrounds, parks and school yards during periods of use and non-use (Idaho Admin. Code r. 58.01.17). Idaho requires the establishment of buffer distances from reuse facilities to protect public health by limiting the public’s exposure to recycled water and conditions associated with reuse facilities and ensuring that the use of recycled water is restricted to within the physical boundaries of the reuse facility (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 relevant rule requirements under the Food Safety Modernization Act (FSMA) (124 Stat. 3885). Treatment requirements and performance standards are applied for the removal of microbial contaminants, chemicals and other relevant indicators for water reuse for landscaping and are summarized in the table below. 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, virus inactivation and turbidity requirements (defined in the table below).
Water reuse for landscaping approved for use in Idaho
Idaho Admin. Code r. 58.01.17 defines the following approved water reuse for landscaping:
- Parks, playgrounds and school yards during periods of use (Class A)
- Residential landscape (Class A)
- Parks, playgrounds and school yards during periods of non-use (Class A and Class B)
- Golf courses (Class A and Class B)
- Highway medians and roadside vegetation on sides (Class A, Class B and Class C)
- Cemeteries (Class A, Class B and Class C)
Water reuse treatment category for landscaping
The various classes of treatment are defined by their respective treatment requirements and applicable performance standards. The respective water reuse treatment requirements are briefly summarized below for landscaping:
- 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.” (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, respectively, 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” (Idaho Admin. Code r. 58.01.17).
In determining buffer distances for inclusion in a reuse permit, Idaho considers the characterization of the recycled water, the irrigation method, the physical or vegetative barriers, microbial risk assessments, applicable best management practices, environmental conditions (e.g., wind speed and direction) and any other relevant information (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 and Class B 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 to indicate that recycled water is being used and is not safe for drinking or human contact (Idaho Admin. Code r. 58.01.17). For Class C municipal recycled water, signs must be posted at the area of use that state “Caution: Recycled Water - Do Not Enter” in both English and Spanish to indicate that recycled water is being used and is not safe for drinking or human contact (Idaho Admin. Code r. 58.01.17).
Water reuse for landscaping specifications
Summary of Idaho's Water Reuse for Landscaping 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 (Parks, playgrounds and school yards during periods of use and during periods of non-use; Golf courses; Residential landscape; Cemeteries; Highway medians and roadside vegetation on sides; and other uses approved on a case-by-case basis) |
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) |
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 |
Weekly |
||
|
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 |
Disinfection requirement |
||
|
Phosphorusb |
Not specified |
Not specified |
||
|
Class B (Parks, playgrounds and school yards during periods of non-use; Golf courses; Highway medians and roadside vegetation on sides; Cemeteries; and other uses approved on a case-by-case basis) |
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 |
Measured at peak flow |
||
|
Nitrogena |
Not specified |
Not specified |
||
|
Phosphorusb |
Not specified |
Not specified |
||
|
Class C (Highway medians and roadside vegetation on sides; Cemeteries; and other uses approved on a case-by-case basis) |
Municipal wastewater |
Total coliform |
≤23 MPN/100 mL (5-day median) ≤230 MPN/100 mL (single sample maximum) |
Once weekly or as determined |
|
Nitrogena |
Not specified |
Not specified |
||
|
Phosphorusb |
Not specified |
Not specified |
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.
a Idaho provides loading limits in place of concentration limits for nitrogen and monitoring typically occurs monthly. Requirements are specified in the associated permit on a case-by-case basis (for more information, contact the state).
b Phosphorous requirements are specified in the associated permit on a case-by-case basis and are determined based on groundwater conditions and connectivity, surface water proximity and connectivity and soil conditions (for more information, contact the state). In some cases, ongoing monitoring is required (for more information, contact the state).
Upcoming state law or policy
No upcoming regulations pertaining to water reuse for landscaping were found for Idaho. Guidance on buffer distances related to the use of recycled water is currently being updated.
References
Clean Water Act, 33 U.S.C. §§ 1251 et seq.
Food Safety Modernization Act (FSMA), 124 Stat. 3885.
Municipal Recycled Water: Classification, Treatment, Use, Idaho Admin. Code r. 58.01.17.601.
Recycled Water Rules, Idaho Admin. Code r. 58.01.17.
Please contact us at waterreuse@epa.gov 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.