Cruise Ship Sewage Disposal Earns Low Marks

When it comes to sewage disposal, cruise ships do not always employ ocean-friendly practices. 

Friends of the Earth (FoE), an environmental watchdog, wrote up a report card this month grading the major cruise companies on their environmental kindness. "Most travelers don’t realize that taking a cruise is more harmful to the environment and human health than many other forms of travel," the report card said. 

The Disney Cruise Line stood alone in receiving an overall A on the report card, which graded sewage treatment, air pollution reduction, and water quality compliance. 

Carnival Cruise Lines received an F for sewage treatment and an overall C-, while Costa, Crystal, MSC and P&O Cruises all received an overall F.

Cruise ships create a lot of sewage.

An EPA survey of cruise ships found the average reported sewage generation rates were 21,000 gallons/day/vessel and 8.4 gallons/day/person. Some cruise ships carry thousands of passengers.  In other words, a 3,000-person cruise ship would generate over 175,000 gallons of sewage per week. 

By FoE's calculations, that is more than enough "to fill 10 backyard swimming pools in a week. That adds up to more than 1 billion gallons a year for the industry — a conservative estimate, since some new ships carry as many as 8,000 passengers and crew.”

FoE described the situation bluntly: "At sea, what you flush down the toilet can actually be dumped untreated into the ocean to contaminate fish and other marine life, so long as the ship is at least three nautical miles from shore."

Some ships use Marine Sanitation Devices (known as Type II MSDs) for sewage treatment, which FoE found problematic.

"Although cruise ships can legally use 30-year-old MSD technology to treat sewage, the U.S. EPA has found that sewage treated with this older technology often contains significant amounts of fecal bacteria, heavy metals, and nutrients in excess of federal water quality standards," the report card said. 

Another more advanced technology ships may use is known as ATWS.  It "provides better screening, treatment, disinfection, and sludge processing." But even AWTS has trouble "removing all dissolved metals and nutrients and can release harmful substances into valuable coastal and marine environment," the report card said. 

Nevertheless, the group advocated for a third option, saying cruise ships opt to hold treated sewage onboard and not dump it out. 

Why are so few cruise ships making the grade? In part because there are very few regulations to rein them in, observers said.

"While cruise ships operating are required to discharge only treated wastewater within three miles of the shore, beyond that limit, pretty much anything goes in terms of sewage discharge," Discovery News recently reported. 

In 2008, the EPA published the Cruise Ship Discharge Assessment Report at the behest of environmentalists. 

The agency says it is assessing the need for additional standards on this front. It is looking at cruise ships operating in Alaska, in particular. That's because Congress mandated such oversight in 2000, but focused only on that single state. 

For previous coverage of the cruise industry on Water Online, click here.