Summary of North Carolina'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 Non-Potable Water Reuse.

On this page:

• Technical basis
• Types of onsite non-potable reuse approved for use in North Carolina
• Water reuse treatment category/type
• Additional context and definitions
• Onsite non-potable reuse specifications (table)
• Upcoming state law or policy
• References
• Disclaimer

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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 North Carolina, onsite non-potable water reuse 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 toilet and urinal flushing, decorative fountains, yard hydrants, vehicle washing, trap primers, fire suppression and clothes washers. The source of water (onsite collected waters) 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 stormwater or rainwater, greywater, blackwater, air conditioning condensate, and foundation water. is specified by the state as graywater. 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

North Carolina approves the use of graywater for beneficial use, including water reuse for onsite non-potable water reuse. Beneficial use applications related to onsite non-potable water reuse purposes include toilet and urinal flushing, decorative fountains, yard hydrants, vehicle washing, trap primers, fire suppression and clothes washers (38 N.C. Admin Code. § 143; NCPC, 2018). 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. In North Carolina, a permit is required to construct, install, alter and repair non-potable water systems, including those used to recycle graywater (NCPC, 2018). Treatment requirements and performance standards are applied for the removal of debris, microbial contaminants, chemicals and other relevant indicators related to onsite non-potable water reuse and are summarized in the table. The technical basis for developing the specifications and/or removal of debris, microbial contaminants, chemicals and other relevant indicators is not explicitly specified.

Types of onsite non-potable reuse approved for use in North Carolina

The North Carolina Plumbing Code (NCPC, 2018) defines the following specific onsite non-potable reuse applications for untreated graywater from non-potable water systems:

• Outdoor irrigation
• Decorative fountains
• Yard hydrants
• Vehicle washing
• Outdoor hose bibs not routed through building wall

The NCPC (2018) defines the following specific onsite non-potable reuse applications for treated graywater from non-potable water systems:

• Toilet flushing
• Urinal flushing
• Trap primers
• Fire suppression systems
• Clothes washers
• Outdoor pools and spas
• Residential hose bibs

Additional onsite non-potable water reuse applications for collected treated municipal wastewater are not specified.

Water reuse treatment category/type

North Carolina does not assign recycled graywater used for onsite non-potable reuse to a category or class. North Carolina permits recycled graywater for onsite non-potable reuse applications, divided by whether the recycled graywater is treated or untreated. Treated graywater specifications are summarized in the table. Untreated graywater does not require adherence to water quality standards but may only be retained in a collection reservoir for a maximum of 24 hours upon collection. Additional water quality requirements may apply depending on the intended application.

Specific treatment requirements are provided for non-potable water systems; however, these requirements are not specific to the use of recycled graywater for onsite non-potable water reuse applications and apply to non-potable reuse applications for additional source water types (e.g., harvested rainwater). These treatment requirements are summarized below:

• Filtration: All onsite non-potable water reuse systems must include a debris excluder or equivalent device to prevent debris from entering the storage tank. Graywater must be further filtered as required for the intended end use (NCPC, 2018). Specifically, non-potable water utilized for water closet and urinal flushing must be filtered by a 100-micron or finer filter (NCPC, 2018). All filtration must have a mechanism to indicate servicing or replacement as well as be installed with shutoff valve immediately upstream and downstream to allow for maintenance (NCPC, 2018).
• Disinfection: North Carolina requires recycled graywater be disinfected as necessary to meet water quality requirements specific for the intended onsite water reuse application, including the minimum treatment requirements provided in the table (NCPC, 2018). Graywater used for flushing water closets and urinals must be disinfected and treated in compliance with NSF 350 Graywater treatment requirements (NCPC, 2018).
• Insects and vermin: All storage tanks must be protected to prevent entrance of insects and vermin into the tank and piping system. Screens installed on vent pipes, inlets and overflow pipes must have an aperture less or equal to 1/16’’ (1.6 mm) and be close-fitting (NCPC, 2018).

Additional context and definitions

North Carolina defines graywater systems as water reuse systems that are contained within a single-family residence or multiunit residential or commercial building that filters graywater and reuses it for non-potable purposes (38 N.C. Admin Code. § 143). North Carolina defines graywater as water that is discharged as waste from bathtubs, showers, wash basins and clothes washers. Graywater does not include water discharged from toilets or kitchen sinks.

All non-potable water storage tanks must be made identifiable with purple piping, embossing or signage with the words “Non-potable water is utilized for [application name]. CAUTION: NONPOTABLE WATER – DO NOT DRINK.” (NCPC, 2018). Further, all non-potable water utilized for indoor onsite uses must be colored blue or green (NCPC, 2018).

The North Carolina Department of Environment and Natural Resources (NCENR) has an established Water Efficiency Manual to support the safe and sustainable use of treated municipal wastewater as well as provide foundation of the basis of specifications (NCENR, 2009).

Onsite non-potable reuse specifications

Summary of North Carolina’s Onsite Non-Potable Reuse Specifications

Source = NCPC (2018)

^a 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.

Upcoming state law or policy

No upcoming onsite non-potable water reuse regulations were found for North Carolina.

References

Clean Water Act, 33 U.S.C. §§ 1251 et seq.

North Carolina Administrative Code (NCAC) Title 15A Environmental Quality, 15A N.C. Admin Code.

North Carolina Department of Environment and Natural Resources (NCDENR). 2009. Water Efficiency Manual.

North Carolina Department of Environmental Quality (NCDEQ). 2023. Water Reuse & Reclamation.

North Carolina Plumbing Code (NCPC). 2018. Chapter 13: Nonpotable Water Systems.

Water Resources, 38 N.C. Admin Code. §143 355.5.

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Disclaimers

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.