What is Blackwater? • Cruise Ships • Friends of the Earth

What is Blackwater?

What is Blackwater?

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Blackwater is commonly dumped in the oceans by cruise ships, but what is blackwater? The answer: human sewage. Thousands of passengers board these large floating hotels to escape their daily lives. But their digestive systems don’t stop. And we all know what happens, what goes in must then come out — a.k.a. everyone has to use the bathroom facilities, even while on vacation. The waste that is gathered from the toilets, urinals, and medical facilities is collected and stored on the ship and goes into a treatment system but if a cruise ship is far enough from shore it can release sewage wastewater without being treated. 

Yes, you read that right. Sewage does not have to be treated to be released into most places in our ocean waters, as long as the ship is about 3.5 miles offshore.  Human waste can literally be dumped into our oceanic ecosystems.

Cruise ship sewage

So how much cruise ship sewage is released into the oceans? It depends on the ship, but the bigger they are, the more passengers and crew there are to generate sewage. On a one-week journey on a medium sized cruise ship, over 200,000 gallons of sewage is collected and at some point must be treated and released into the sea or discharged onshore, but most is released into the sea.  In all cases, cruise ships are required to have sewage treatment facilities where the solids in sewage are filtered out and chemicals are added to the liquid waste to kill bacteria, but not all of these ships have the newest treatment systems. And in many cases, even the newest treatment systems don’t function properly, leading to large amounts of toxic sewage wastewater dumped onto corals and other vulnerable marine ecosystems. This means that more than one billion gallons of untreated or partially treated sewage is discharged from large cruise ships into our oceans every year. 

We know that human waste is not something you should be swimming around in. It is full of pathogens that are foreign to the ocean environment but are being introduced anyway. Bacteria, intestinal parasites, chemicals, pharmaceuticals, and other toxins can be dumped into our ocean waters with little to no treatment at all. The oceans and all creatures who call them home are without a voice, allowing the cruise industry to dump human waste in their habitat, polluting everything in their path. 

Where does cruise ship sewage go?

Cruise ship blackwater is collected from toilets, medical facilities, and even dishwashers (due to the grease content). The implications on our marine wildlife, waters, and coastal communities poses a concerning risk. 

As we explored above, wildlife including coral, marine mammals, sea turtles, and fish are directly affected by the vast amount of discharge lingering in the ocean. The blackwater is also filled with phosphorus and nitrogen — among other things — that increases algae growth. This is leads to an entirely different problem for ocean life! Just like humans and other terrestrial animals, marine organisms need oxygen to survive. This growing algae consumes oxygen which is a necessary element for corals and other marine wildlife. As oxygen is quickly depleted from the water due to this oxygen-greedy algae, we see more and more dead fish and mammals wash ashore. Not only does this algae cause issues for marine animals, but it also causes health issues for humans!  

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Additionally, fish and shellfish have been impacted by sewage contamination. If they don’t suffocate or die from losing their food sources from lack of oxygen, they continue ingesting the sewage that is present in their environment. After fisherfolk capture them for consumption these creatures now pose a greater human health risk through waterborne ingested illnesses.  

But the impacts to human health go further than that. Just because the ships are supposed to treat sewage waste dumped close to shore doesn’t mean that it actually happens, and waste dumped further out can definitely impact humans swimming closer to the coasts.  

Would you hop into a pool after a toddler had a messy accident in it or would you wait until it was cleaned up properly? Our guess is that you’d prefer to avoid swimming in fecal matter, but when you hop into the ocean, you’re doing just that. Water is obviously fluid and doesn’t stay in one place. The waves carry the water filled with human waste toward coastal communities. Enjoy surfing or water sports or even just dipping your toes in the gorgeous ocean water? Sadly, you could be taking a dip in the water filled with the excrements from cruise ship passengers. Surfers and beachgoers can easily ingest water that is filled with sewage making them sick. 

Do cruise ships dump blackwater in the ocean?

Yes. Unfortunately, blackwater (a.k.a. sewage, human waste) can be dumped into the water untreated as long as the ship is at least 3.5 miles from shore. And cruise ships can take full advantage of not having to treat the waste before releasing it from their ships while they are in the open ocean. 

Graywater vs Blackwater

While we’ve explored that blackwater is sewage, there’s another type of pollution that’s released into the oceans as well. Graywater is the wastewater from showers, sinks, bathtubs, and washing machines. It contains less contaminants than blackwater, but don’t be fooled — it also does harm to the waters that it’s dumped into.  

Graywater can contain medical and dental waste, food waste, bacteria, detergents, oil and grease, and other materials that are not native to aquatic ecosystems.  

Cruise ship sewage

Cruise ships dump sewage directly into the oceans. There’s no easy way to put it. These mega floating cities are filled with people who are utilizing the facilities and basically flushing the toilets right into the water. Despite the harm, it is completely legal for cruise ships to continue with this toxic dumping. 

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