Summary of Hawai'i'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.
- Technical basis
- Applications of centralized non-potable reuse approved for use in Hawai'i
- Water reuse treatment/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 Hawai'i, 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 dust control, toilet and urinal flushing, cleaning and firefighting, 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 recycled water. 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
Hawai'i approves the use of recycled water for centralized non-potable reuse applications including dust control, cleaning and firefighting (Hawai'i State DOH, 2016b). 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 related to centralized non-potable reuse and are summarized in the table. Hawai'i used California’s Title 22 Water Recycling Criteria (Cal. Code Regs. tit. 22) to determine acceptable filtration and disinfection units and the technical basis for developing the other specifications and/or removals of microbial contaminants, chemicals and other relevant indicators is not explicitly specified.
Applications of centralized non-potable reuse approved for use in Hawai'i
Hawai'i State DOH (2016b) defines the following approved centralized non-potable uses:
- Dust control, including dampening, wet sweeping and/or wash-down of streets, roads, parking lots, walkways, etc. (R-1)
- Flushing of toilets, urinals and sanitary sewers where permitted by the county plumbing code (R-1)
- Cleaning, including high pressure water cleaning of surfaces (R-1)
- Firefighting (R-1)
- Washing aggregate and concrete manufacturing (R-1)
- Water jetting to consolidate backfill material around piping for recycled water, non-potable water, sewage, storm drains, gas and electrical conduits (R-1)
Water reuse treatment/type
The various classes of treatment for recycled water are defined by their level of treatment (Hawai'i State DOH, 2016a).
- For R-1 recycled water, wastewater must be oxidized, filtered and disinfected. The limits specified in the table are set based on system size. Filtration standards are based on the specific technology used.
- Disinfection may be achieved by chlorination, UV or another method that, when combined with filtration, has demonstrated inactivation and/or removal of 99.999% (i.e., 5-log) of plaque-forming units of F-specific bacteriophage MS2, polio virus or another virus that is at least as resistant to disinfection as the polio virus.
Additional context and definitions
Hawai'i defines recycled water as “treated wastewater that by design is intended or used for a beneficial purpose” (Haw. Code R. § 11-62).
Components of recycled water systems such as piping, valves, valve covers, etc., must be identified to distinguish them from potable water systems, preferably by being purple in color (Pantone 512 or equal). Where color identification is not feasible, components should be labeled with the words “Recycled Water,” “Recycled Water – Do Not Drink,” or similar (Hawai'i DOH, 2016b). Signage must also be posted with both written and pictorial warnings that indicate the quality of the recycled water, its end use and an appropriate warning against human consumption and/or what to do if contact occurs. Signs must be posted in clear view of the public along the border of and within the use area with a recommended maximum spacing of 250 feet between signs.
Centralized non-potable reuse specifications
Summary of Hawai'i'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)* |
|---|---|---|---|---|
|
R-1 recycled water (Dust control; cleaning; firefighting) |
Municipal wastewater or wastewater from a private plant |
5-day biochemical oxygen demand (BOD5) |
≤5 mg/L (recommended target) ≤30 mg/L (monthly composite average for large non-pond systems) ≤60 mg/L (single sample maximum, all systems) |
Weekly sampling for systems with average daily flow of ≥100,000 gallons/day; monthly sampling for <100,000 gallons/day |
|
Total suspended solids (TSS) |
||||
|
Turbidity (for media filtration) |
≤2 NTU (24-hour average) ≤5 NTU (72 minutes within a 24-hour period) ≤10 NTU (single sample maximum) |
Continuous monitoring both prior to filtration and after filtration but before disinfection |
||
|
Turbidity (for membrane filtration) |
≤0.2 NTU (72 minutes within a 24-hour period) ≤0.5 NTU (single sample maximum) |
|||
|
Turbidity (for reverse osmosis) |
||||
|
Total chlorine residuala (CT) |
≤450 mg-min/L at all times ≥90 minutes (modal contact time) |
Continuous monitoring |
||
|
UV disinfectionb (for media filtration) |
≥100 mJ/cm2 (design dose under maximum daily flow) ≥55% (transmittance at 254 nm) |
Not specified |
||
|
UV disinfectionb (for membrane filtration) |
≥80 mJ/cm2 (design dose under maximum daily flow) ≥65% (transmittance at 254 nm) |
|||
|
UV disinfectionb (for reverse osmosis) |
≥50 mJ/cm2 (design dose under maximum daily flow) ≥90% (transmittance at 254 nm) |
|||
|
F-specific bacteriophage MS2 |
99.999% removal (PFU) |
Not specified |
||
|
Polio virus |
99.999% removal |
Not specified |
||
|
Another virus at least as resistant to disinfection as the polio virus |
99.999% removal |
Not specified |
||
|
Fecal coliforms |
≤2.2 per 100 mL (7-day median) ≤23 per 100 mL (30-day single sample maximum) ≤200 per 100 mL (single sample maximum) |
Daily; may be reduced to weekly under certain conditions |
Source = Haw. Code R. § 11-62; Hawai'i State DOH, 2016a
* 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 Where chlorination is used for disinfection.
b Where UV is used for disinfection. The minimal acceptable design requirements and commissioning of new UV disinfection systems shall comply with the latest Ultraviolet Disinfection Guidelines for Drinking Water and Water Reuse prepared by the National Water Research Institute and Water Research Foundation that has been accepted for use by the Hawai'i Department of Health; a UV system that is Title 22 certified by California is also acceptable.
Upcoming state law or policy
No upcoming regulations pertaining to centralized non-potable reuse were found for Hawai'i.
References:
Clean Water Act, 33 U.S.C. §§ 1251 et seq.
Hawai'i State Department of Health (DOH) Wastewater Branch. 2016a. Reuse Guidelines Volume 1: Recycled Water Facilities.
Hawai'i State Department of Health (DOH) Wastewater Branch. 2016b. Reuse Guidelines Volume 2: Recycled Water Projects.
Wastewater Systems, Haw. Code R. § 11-62.
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.