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Please note: This summary is provided to help you understand the regulations. Consult the references provided for links to the full text of the regulations.


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Graywater is wastewater, typically wash water, that contains contaminants that make it unfit for drinking water, but is not expected to contain highly infectious material, as with sewage. ("Gray" refers to its intermediate status between clean, or "white" water and sewage, or "black" water.) Sources of graywater on vessels include wastewater from galley, laundry, shower, and sink drains. Typical contaminants include soaps and detergents, food scraps, and relatively low levels of microorganisms.

Regulations impacting graywater discharges in U.S. waters are implemented by the U.S. Environmental Protection Agency (EPA). EPA's National Pollutant Discharge Elimination System (NPDES) vessels program regulates graywater and other incidental discharges from the normal operation of vessels.

Who is covered by the regulations?

Any vessel that is subject to regulation under the Vessel General Permit (VGP) must follow the rules specified in the permit when discharging graywater. The VGP applies to all vessels 79 feet or longer, except for military and recreational vehicles.

Vessels operating in certain areas may be required to follow additional state and territorial requirements. These additional requirements are listed in section 6 of the 2013 VGP.

Please Note: The EPA issued the 2013 VGP on April 12, 2013, with an effective period of December 19, 2013, to December 18, 2018 (i.e., five years). On December 4, 2018, the President signed into law the Vessel Incidental Discharge Act (VIDA). VIDA requires EPA to develop new national standards of performance for commercial vessel incidental discharges and the U.S. Coast Guard (USCG) to develop corresponding implementing regulations. The VIDA legislation also extended the 2013 VGP's provisions, leaving them in effect until new regulations are final and enforceable.

What is the purpose of the regulations?

Although graywater generally poses less of an immediate threat to human health than sewage, uncontrolled releases can create significant problems. Graywater can be a rich source of nutrients for aquatic organisms. For example, soaps and detergents contain phosphate, which is less abundant in nature than many other essential nutrients, and often serves as a limiting factor controlling the growth of algae. When phosphate-rich water is discharged, algae will grow more rapidly than other organisms, feeding other organisms low on the food chain. This rapid growth depletes the oxygen in the water, a situation which can be deadly for slower-responding organisms higher on the food chain. This can lead to ecological problems such as fish kills, and can affect human health (some algal blooms generate toxins that can contaminate shellfish).

The problems become most acute near shore, and wherever contaminants can accumulate. Accordingly, the rules are particularly concerned with discharges close to shore.


EPA's NPDES vessels program regulates incidental discharges from the normal operation of vessels using the Vessel General Permit or VGP. These discharges include, but are not limited to, bilgewater, ballast water, graywater (e.g., water from sinks, showers), and deck runoff/washdown.

The VGP requires that vessel owners and operators meet certain requirements, including seeking coverage for most vessels, assuring their discharges meet effluent limits and related requirements, corrective action process for fixing permit violations, and requirements for inspections, monitoring, recordkeeping and reporting.

Graywater discharges are subject to the rules found in section 2.2.15 of the VGP. Readers are urged to download the VGP and read it before taking any action. The following is a summary of the VGP regulations covering the discharge of graywater:

  • All vessels must minimize the discharge of graywater while in port and not discharge it, if they have the capacity to store it.
  • For vessels greater than 400 gross tons that regularly travel more than 1 nm from shore that have the capacity to store graywater for a sufficient period, graywater must be discharged greater than 1 nm from shore while the vessel is underway, unless the vessel meets the treatment standards.
  • Vessels that do not travel more than 1 nm from shore must minimize the discharge of graywater and, provided the vessel has available graywater storage capacity, must dispose of graywater on shore if appropriate facilities are available and such disposal is economically practicable and achievable unless the vessel meets the treatment standards.
  • If graywater will be discharged, the introduction of kitchen oils must be minimized to the graywater system.
  • Vessel owner/operators must use phosphate free and non-toxic soaps and detergents.
  • If you are underway in a nutrient impaired water, or a water that is impaired as a result of nutrient enrichment (such as waters listed as impaired for phosphorus, nitrogen, or for hypoxia or anoxia (low dissolved oxygen concentrations)) you must follow additional steps outlined in the permit
  • When the vessel has adequate graywater storage capacity, the vessel owner/operator shall not discharge graywater into nutrient impaired waters.
  • The following discharge standards must be met:
    • The discharge must satisfy the minimum level of effluent quality specified in 40 CFR 133.102 (secondary treatmentstandards),
    • The geometric mean of the samples from the discharge during any 30-day period may not exceed 20 fecal coliform/100 milliliters (ml) and not more than 10 percent of the samples exceed 40 fecal coliform/100 ml, and
    • Concentrations of total residual chlorine may not exceed 10.0 micrograms per liter (μg/l).

It is important to note that the commingled discharge of graywater mixed with sewage from vessels must comply with the effluent limits for graywater discharge in the VGP and the requirements set forth in section 312 of the Clean Water Act and its implementing regulations found at 40 CFR Part 140 and 33 CFR Part 159. Discharges of graywater mixed with sewage must meet both standards to be in compliance.

Cruise ships, which can carry as many as 3,000 passengers and crew members, and often operate in pristine coastal waters present a special regulatory challenge. Some additional rules for cruise ships operating in Alaska are already in place. EPA is continuing to assess wastewater discharges from cruise ships and reviewing regulatory options for additional control.

In addition to the requirements of the federal VGP, vessel owners/operators must comply with all applicable state environmental regulations governing graywater discharges.

Best Practices

U.S. EPA VGP regulations are founded on best management practices. Please refer to the regulations summarized above.

More Resources

EPA VGP Points of contact:

Additional, related documents: