Summary of Oklahoma'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 Oklahoma
- 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 Oklahoma, 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 toilet and urinal flushing, fire protection and concrete mixing, 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 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 centralized non-potable reuse applications including, but not limited to, toilet and urinal flushing, fire protection, vehicle and equipment washing, concrete mixing, dust control and soil compaction (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 in addition to any state water quality standards. Treatment requirements and performance standards are applied for the removal of pathogen and chemical contaminants for centralized non-potable reuse applications. The technical basis for the removal of pathogen and chemical contaminants is not explicitly specified.
Applications of centralized non-potable reuse approved for use in Oklahoma
Okla. Admin. Code § 252:656-27 defines the following approved centralized non-potable reuse applications:
- Toilet and urinal flushing (Category 2)
- Fire protection systems (Category 2)
- Commercial closed-loop air conditioning systems (Category 2)
- Vehicle and equipment washing, excluding self-service car washes (Category 2)
- Concrete mixing (Category 3)
- Dust control (Category 3)
- Aggregate washing/sieving (Category 3)
- Soil compaction and similar construction activities (Category 4)
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:
- 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 a 5-log removal of Adenovirus type 15, a 5-log removal of Salmonella typhimurium and a 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 a storage detention time of at least 90 days following primary treatment.
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.
Centralized non-potable reuse specifications
Summary of Oklahoma'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)* |
|---|---|---|---|---|
|
Category 2 (toilet and urinal flushing, fire protection systems, commercial closed-loop air conditioning systems, vehicle and equipment washing) |
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/100 mL (single sample maximum) |
Daily |
||
|
Total N |
“≤ most stringent agronomic rate” |
Monthly |
||
|
Total P |
“≤ 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 (concrete mixing, dust control, aggregate washing/sieving) |
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 N |
“≤ most stringent agronomic rate” |
Monthly |
||
|
Total P |
“≤ 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 (soil compaction and similar construction activities) |
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 ppm (combined chlorine residual) |
Daily, measured at the POE |
||
|
Dissolved oxygen (DO) |
>2.0 mg/L |
Weekly |
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.
Upcoming state law or policy
No upcoming regulations pertaining to centralized non-potable reuse 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.
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.