Gray Water in the Antarctic

Despite its known toxicity, untreated gray water from ships is routinely discarded in the Southern Ocean. There are no regulations to limit its release anywhere in the Antarctic.

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What is gray water?

Gray water is one of the largest sources of wastewater generated by ships, and is produced as part of normal operations on fishing, tourism, research, and supply vessels operating in the Antarctic.

The highest volumes of gray water come from vessels with the most passengers, and those who spend the longest in the Antarctic. As human activity in the region continues to increase, so does the amount of gray water produced, and released into the ocean. Estimates of daily gray water production on passenger vessels range from 36 to 119 gallons (136 to 450 liters) per person, per day (Source).

Where does gray water come from?

Ships produce gray water via several pathways, including showers, baths, wash basins, washing machines and dishwashers.

Gray water may also come from other plumbing systems, such as sinks and floor drains in medical facilities or salons; deck drains in non-engine rooms, for example chemical storage areas; and refrigerator, air conditioner and dry-cleaning condensate, among others.

What is in gray water?

Gray water can contain a range of pollutants harmful to marine ecosystems, including microplastics, heavy metals and chlorine.

Depending on its source, gray water can contain food waste; high levels of nutrients; oil and grease; pharmaceuticals including antibiotics; chemicals found in cleaning products such as chlorine; microplastics; heavy metals; xenobiotic organic compounds (XOCs); and other contaminants toxic to marine life.

The pH, salinity, and turbidity of gray water varies between sources, with temperatures ranging from 64 to 95°F (18 to 35°C) – significantly above the average temperature of the Southern Ocean (Source).

Why is it important?

The Antarctic is particularly vulnerable to pollutants in gray water due to the unique characteristics of polar waters, such as cold temperatures and long periods of darkness.

When gray water enters the ocean it is gradually dispersed, and slowly degrades over many years. This happens most quickly in the presence of light and warm ocean temperatures. The Antarctic experiences minimal to low light for approximately six months of the year, and very low temperatures from 28 to 50°F (-2 to 10°C), both of which slow the decomposition of gray water. Some pollutants found in gray water, such as microplastics and heavy metals, never decompose.

Polar waters are also highly vulnerable to changes in the nutrient status of the water column or seabed. The introduction of excess nutrients in gray water increases their availability for uptake by algae, which can lead to a cascade of events such as algal blooms, ocean acidification, loss of biodiversity, and disruption of food webs. In cases of severe over-enrichment, oxygen-depleted dead zones can be created.

Other components of gray water, including its elevated temperature relative to the Southern Ocean, and contaminants which may be present such as chlorine, heavy metals, microplastics, and xenobiotic organic compounds (XOCs), can cause damage to marine organisms.

Download our infographic: Gray Water and Microplastics – The Problem and The Solution.

Analyses of gray water from passenger vessels have found pathogens such as fecal coliform in concentrations up to three orders of magnitude greater than those typical in untreated domestic wastewater.
Source: United States Environmental Protection Agency (2008)

humpback whale — Humpback whale Megaptera novaeangliae. Image credit: Canva.com

Despite the known toxicity of many of its constituents, ships can release gray water anywhere across the Antarctic without restrictions.

While some sources of shipping wastewater, such as sewage and ballast water, are regulated by the International Maritime Organization (IMO), gray water has been overlooked. It is not regulated at the global level, and is not currently under consideration by the IMO.

Chinstrap penguins porpoising. — Chinstrap penguins (Pygoscelis Antarcticus) porpoising. Image credit: Canva.com.

Recognising the threat presented by gray water, some nations have taken matters into their own hands. Both the United States and Canada have introduced local regulations to control gray water disposal and protect vulnerable coastal ecosystems. The same could be done in Antarctica.

At an annual meeting of Antarctic decision makers in 2024, ASOC drew attention to the growing problem of unregulated gray water disposal in the Antarctic. Several parties expressed an interest in working together to better understand the impacts of gray water in the Antarctic, and discuss potential solutions.

MANAGING GRAY WATER

You can help

With the generous support of our global community, ASOC will continue to urge decision makers to address the threat posed by unregulated gray water in the Antarctic.

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Within the Antarctic Treaty System

Each year, representatives from over 50 nations gather to make decisions about the future of Antarctica.

ASOC attends this forum as an invited expert, representing our members and the broader global conservation community. We advocate for strong environmental protection for Antarctica, and draw attention to issues that may otherwise be overlooked.

At the 2024 Antarctic Treaty Consultative Meeting, ASOC submitted an Information Paper highlighting concerns about unregulated gray water disposal.

The prevention of pollution and management of waste in the Antarctic Treaty Area is addressed by the Protocol on Environmental Protection to the Antarctic Treaty. While the Protocol makes no specific reference to gray water, it does prohibit the disposal of ‘all plastics’ into the sea. This could include liquids containing microplastics, such as gray water. Clear, specific regulations relating to gray water disposal are needed.

ASOC will continue to present information about the impacts of unregulated gray water on the Antarctic environment and ecosystems, and urge Parties to address this significant source of wastewater from ships.

Read the 2024 Information Paper on gray water.

Learn about the Antarctic Treaty System.

Within CCAMLR

ASOC monitors all issues that impact the Antarctic environment, including plastic pollution, fisheries management, biological prospecting and pirate fishing.

As the only official environmental NGO observer at CCAMLR meetings, we present science-based policy proposals and provide decision makers with reliable information on how to protect Antarctic wildlife and the environment.

This includes raising awareness of largely overlooked sources of marine pollution and toxicity, such as gray water.

Learn more about CCAMLR.

International Maritime Organization

The International Maritime Organization is an agency of the United Nations charged with regulating global shipping, including the prevention of pollution.

The International Convention for the Prevention of Pollution from Ships (MARPOL), adopted in 1978, introduced legally binding measures to prevent pollution from ships.

Today, regulations are in place for sewage, ballast water, bilge water, and several other waste water streams from shipping. Despite the known contaminants present in gray water, it has been consistently overlooked.

ASOC continues to work with member and partner organizations to raise the profile of gray water at meetings of the IMO, and to remind governments of the urgent need to regulate this harmful pollutant.

The Polar Code

The International Code for Ships Operating in Polar Waters (Polar Code) aims to promote safe practices and avoid environmental damage in the remote and sensitive polar regions.

ASOC continues to participate in international meetings where the Polar Code is on the agenda. We present decision-makers with policy papers backed by the best available science, advocating for strong protection for Antarctic marine ecosystems.

Read about our campaign to strengthen the Polar Code.

Learn more about the Polar Code.

Your gift makes a difference! Thanks to the generous support of our global network, ASOC continues to advocate for stronger environmental protection for Antarctica and its ecosystems.

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