Summary of Oklahoma'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 Oklahoma
- 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 Oklahoma, 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 spray or drip irrigation of public access landscapes and public use areas/sports complexes, including unrestricted access golf courses; irrigation of restricted access landscapes; new restricted access golf course irrigation systems; and existing restricted access golf course irrigation systems whose reclaimed water is provided by lagoon systems. 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
Oklahoma approves the use of reclaimed water for water reuse for landscaping, including the irrigation of public access landscapes, golf courses with various access restrictions and other public use areas and sports complexes (Okla. Admin. Code § 252:656). All applicable provisions of the Clean Water Act (CWA) (33 U.S.C. §§ 1251 et seq.), including its implementing regulations, must be met. Oklahoma requires specific treatment for the reuse of reclaimed water for landscaping in areas where public access is expected. 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. For example, log-removal treatment targets for viruses (5-log for Adenovirus type-15), bacteria (5-log Salmonella typhimurium) and protozoa (3-log Giardia lamblia) are required for Category 2. The technical basis for developing the specifications and/or removals of microbial contaminants, chemicals and other relevant indicators was the product of a workgroup including regulatory agencies, local consultants and national water reuse experts. The specific removal targets for each organism considered the expected load to be seen by the disinfection system following the preceding treatment barriers and the effluent levels that should be safe given the expected level of exposure for the given reuse activities within that category (Oklahoma DEQ, personal communication, May 31, 2022).
Water reuse for landscaping approved for use in Oklahoma
Okla. Admin. Code § 252:656-27 defines the following approved water reuse for landscaping:
- Spray or drip irrigation of public access landscapes (Category 2)
- Spray or drip irrigation of public use areas/sports complexes, including unrestricted access golf courses (Category 2)
- Irrigation of restricted access landscape (Category 3)
- New restricted access golf course irrigation systems (Category 3)
- Existing restricted access golf course irrigation systems whose reclaimed water is provided by lagoon systems (Category 4)
Water reuse treatment category for landscaping
The various classes of treatment are defined by their respective treatment requirements and applicable performance standards. The respective treatment requirements are briefly summarized for water reuse for landscaping.
- For Category 2 reclaimed water, the treatment requirements are secondary treatment, nutrient removal, coagulation, filtration, continuous turbidity measurements using online turbidimeters and disinfection by chlorination or a combination of chlorination and UV. The method of disinfection shall achieve 5-log removal of Adenovirus type 15, 5-log removal of Salmonella typhimurium and 3-log removal of Giardia lamblia.
- For Category 3 reclaimed water, the treatment requirements are secondary treatment, nutrient removal and disinfection by chlorination.
- For Category 4 reclaimed water, the treatment requirements are primary treatment, disinfection by chlorination and storage detention time following primary treatment. Permits to construct new Category 4 restricted golf course irrigation systems shall not be issued pending further research and evaluation of performance data collected from existing systems (Okla. Admin. Code § 252:656).
Additional context and definitions
Oklahoma defines reclaimed water as “wastewater that has gone through the various treatment processes to meet specific water quality criteria with the intent of being used in a beneficial manner” (Okla. Admin. Code § 252:656).
Oklahoma requires that municipal reclaimed water permittees prevent any physical connections between reclaimed water lines and public water supply lines (Okla. Admin. Code § 252:656). Separation distances are required from public wells (300 feet), private wells (50 feet), waters of the state (25 feet for Category 2 reclaimed water and 50 feet for Categories 3 and 4 reclaimed water) and property lines (20 feet for Category 2 reclaimed water and 100 feet for Categories 3 and 4 reclaimed water). As of July 2012, all reclaimed water piping, valves and outlets are required to be colored purple and must be embossed or stamped on opposite sides every three feet with warning language that includes “CAUTION: RECLAIMED WATER – DO NOT DRINK.” For reclaimed water systems installed prior to July 2012, there must be, at minimum, above-ground signs containing the warning language in the previous sentence along with the international “Do Not Drink” symbol every 300 feet, at every change in direction, in the road easement on both sides of every road crossing and at every outlet.
Water reuse for landscaping specifications
Summary of Oklahoma's Water Reuse for Landscaping Specifications
| Recycled Water Class/Category (Approved Uses) | Source Water Type | Water Quality Parameter | Specification | Sampling/Monitoring Requirements (Frequency of monitoring; site/ location of sample; quantification methods)* |
|---|---|---|---|---|
|
Category 2 (Spray or drip irrigation of public access landscapes; Spray or drip irrigation of public use areas/sports complexes, including unrestricted access golf courses) |
Municipal wastewater |
Turbidity |
≤2 NTU (daily average) ≤2 NTU (> 5% of daily maximum per month) ≤10 NTU (single sample maximum) |
Continuous monitoring. The daily mean operating filter effluent turbidity (continuously monitored) is calculated as the average of turbidity measures at ≤ 1.2-hour intervals over 24 hours and must be reported monthly. The maximum 24-hour turbidity must be based on highest measure from continuous monitoring taken at ≤ 1.2-hour intervals over 24 hours. |
|
Chlorine residual (at POEa to distribution system) |
≥1.0 ppm (free available chlorine residual) or “the chlorine residual at the POE shall be at a level to prevent growth of slime and regrowth of pathogens in the distribution and storage systems as determined by an approved chlorine decay rate model pursuant to OAC 252:656-3-4 (b)(7)(C)” |
Continuous monitoring |
||
|
Chlorine residual (at end-of-pipe) |
≥0.20 mg/L (free available chlorine residual) or ≥0.50 mg/L (combined chlorine residual) |
Daily |
||
|
Fecal coliform |
0 CFU/100 mL (in four of the last seven daily samples) ≤23 CFU/100mL (single sample maximum) |
Daily |
||
|
Total Nitrogen |
"≤ most stringent agronomic rate" |
Monthly |
||
|
Total phosphorus |
"≤ most stringent agronomic rate" |
Monthly |
||
|
5-day carbonaceous biochemical oxygen demand (CBOD5) |
<5 mg/L |
Weekly |
||
|
Adenovirus type 15 |
5-log removal or inactivation |
The method of disinfection must achieve these removals |
||
|
Salmonella typhimurium |
5-log removal or inactivation |
|||
|
Giardia lamblia |
3-log removal or inactivation |
|||
|
Category 3 (Irrigation of restricted access landscape; New restricted access golf course irrigation systems) |
Municipal wastewater |
Chlorine residual |
≥0.20 mg/L (free available chlorine residual) or ≥0.50 mg/L (combined chlorine residual) |
Every 12 hours, measured at the POE |
|
Fecal coliform |
<200 coli/100 mL (monthly geometric mean) <400 coli/100 mL (single sample maximum) |
3 times/week |
||
|
Total Nitrogen |
"≤ most stringent agronomic rate" |
Monthly |
||
|
Total phosphorus |
"≤ most stringent agronomic rate" |
Monthly |
||
|
5-day biochemical oxygen demand (BOD5) or 5-day carbonaceous biochemical oxygen demand (CBOD5) |
<20 mg/L |
Weekly |
||
|
Category 4 (Existing restricted access golf course irrigation systems) |
Municipal wastewater |
Fecal coliform |
<200 coli/100 mL (monthly geometric mean) <800 coli/100 mL (single sample maximum) |
Weekly |
|
Chlorine residual |
≥0.20 ppm (free available chlorine residual) or ≥0.50 (combined chlorine residual) |
Daily, measured at the POE |
||
|
Dissolved oxygen (DO) |
>2.0 mg/L |
Weekly |
||
|
Nitrogenb |
Not specified |
Not specified |
||
|
Phosphorusb |
Not specified |
Not specified |
Source= Okla. Admin. Code § 252:656 and § 252:627
* 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 POE= point of entry
b In Oklahoma, nutrient management related to reclaimed water systems is achieved by evaluating agronomic loading rates for each specific cover crop or turf variety.
Upcoming state law or policy
No upcoming regulations pertaining to water reuse for landscaping were found for Oklahoma.
References
Clean Water Act, 33 U.S.C. §§ 1251 et seq.
Operation and Maintenance of Water Reuse Systems, Okla. Admin. Code § 252:627.
Water Pollution Control Facility Construction Standards, Okla. Admin. Code § 252:656.
Wastewater Reuse, Okla. Admin. Code § 252:656-27.
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.