Summary of Hawai'i's Water Reuse Guideline or Regulation for Onsite Non-Potable Water 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 Onsite Collected Waters.
- Technical basis
- Types of onsite non-potable reuse approved for use in Hawai'i
- Water reuse category/type
- Additional context and definitions
- Onsite non-potable reuse specifications
- 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, onsite non-potable water reuse The use of treated onsite collected waters for non-potable purposes at the single-building or district scale. This reuse application excludes the use of recycled water from a centralized treatment and distribution system for landscape irrigation or commercial uses. applications include residential subsurface landscape irrigation. The source of water onsite collected waters Water sources generated within or surrounding a building, residence, or district. Other terms referring to this source of water include onsite collected rainwater, greywater, blackwater, air conditioning condensate, and foundation water. is specified by the state as gray 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.
Check out Hawai'i's other onsite non-potable water reuse summary!
State requirements for water quality and treatment are often associated with the source water. Hawai'i has an onsite non-potable water reuse summary page where the source water is rainwater collected onsite.
Technical basis
Hawai'i allows the onsite non-potable reuse of gray water for residential subsurface landscape irrigation and the Hawai'i Department of Health (DOH) developed gray water reuse guidelines in 2009 for homeowners of single-family dwellings (Hawai'i DOH, 2009). Gray water reuse systems in Hawai'i should comply with Chapter 16 (Gray Water Systems) of the Uniform Plumbing Code (2006) with some modifications, including the allowance of washing machine wastewater to be used for subsurface irrigation (Hawai'i DOH, 2009). 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 2009 DOH guidance and 2006 Uniform Plumbing Code provide details on gray water system design considerations (e.g., general design requirements, estimating gray water discharge, collection and holding, subsurface distribution, inspection and testing and maintenance). However, neither the 2009 DOH guidance or 2006 Uniform Plumbing Code provide explicit specifications for removal of chemical or microbial contaminants for gray water reuse systems.
Types of onsite non-potable reuse approved for use in Hawai'i
Hawai'i DOH (2009) lists the following acceptable uses onsite non-potable uses for gray water:
- Subsurface landscape irrigation of the property the gray water was generated from (except areas where there is a potential for runoff and/or ponding).
Water reuse category/type
Hawai'i does not assign gray water used for onsite non-potable reuse to a category or class.
Additional context and definitions
Hawai'i defines gray water as “wastewater discharged from showers, bathtubs, hand-washing lavatories, wastewater that has not contacted toilet waste, sinks (not used for the disposal of hazardous, toxic materials, food preparation, or food disposal) and clothes washing machines excluding wash water with human excreta (e.g., diapers)” (Hawai'i DOH, 2009).
Onsite non-potable reuse specifications
Hawai'i does not have explicit specifications for onsite non-potable water reuse applications.
Upcoming state law or policy
Hawai'i is in the early stages of developing onsite regulations for dual plumbed buildings.
References:
Clean Water Act, 33 U.S.C. §§ 1251 et seq.
Hawaii State Department of Health (DOH) Wastewater Branch. 2009. Guidelines for the Reuse of Graywater.
Relating to Onsite-Non-Potable Water Reuse Systems, Haw. H.B. 444 (2019).
Uniform Plumbing Code. 2006. Chapter 16: Gray Water Systems.
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.