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How Do Cruise Ships Get Fresh Water?

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Cruise ships need a lot of fresh water. Think about all the water required for thousands of passengers to drink, shower, and cook.

But how do cruise ships get fresh water out in the middle of the ocean?

Cruise ships produce drinking water through steam evaporation or reverse osmosis. The cruise ship adds minerals and chlorine to the desalinated water for taste and added safety.

Keep reading to learn more about how cruise ships get fresh water.

How Do Cruise Ships Get Fresh Water?

A glass of water sitting on a table next to a white bed in the morning, wake up routine.

Cruise ships get fresh water through a special filtering process that desalinates ocean water. Cruise ships use steam or reverse osmosis to remove salt before adding minerals and chlorine for flavor and safety.

Ships also use large water stores, which can be pumped on board at the port. 

Steam Evaporation

Steam evaporation, also known as steam desalination or flash evaporation, uses the cruise ship engine’s heat to boil seawater.

When saltwater turns to steam, the water separates from the salt, leaving behind freshwater. Condensers collect the steam as distilled water.

Cruise ships use a multi-stage flash evaporator that repeats the process three or four times for added safety.

Steam evaporation systems take up a lot of space and require a lot of energy. A steam desalination system is the most commonly used process because it produces a high volume of fresh drinking water.

Reverse Osmosis

Reverse osmosis is another commonly used method to produce freshwater on cruise ships. Reverse osmosis is a low-energy method that passes seawater through several filters at high pressure.

Ocean water is first passed through a course filter to remove mud, shells, and other large contaminants before moving through a sand filter.

After removing large impurities, the seawater is passed through a microscopic membrane. The membrane is small enough to allow water to pass through, but it catches any salt content or contaminants.

The process works similarly to a home water filter but on a large enough scale to provide water to thousands of people.

Onboard reverse osmosis plants have a smaller footprint than steam evaporators and require less energy. However, reverse osmosis has a lower capacity. Cruise ships that rely on reverse osmosis systems may be equipped with two water treatment plants.

Water Bunkering

The demand for fresh water on cruise ships often exceeds what can be produced by the ship’s freshwater systems. Cruise ships have clean water stores onboard to meet the demand. The freshwater stores are replenished at the port.

Water bunkering is essential for cruise ships as the water treatment plants can only operate while sailing.

A cruise ship may spend eight or more hours in port. During that time, the only source of freshwater is the cruise ship’s water stores.

Cruise ships normally bunker, or store, water on a weekly basis, receiving water at their homeport. Cruise ships may receive freshwater at ports of call but never from countries with a water shortage.

Before the water is transported onto the ship, it is checked for quality and treated.

Is Cruise Ship Water Safe to Drink?

A woman drinking a glass of fresh water

Cruise ship tap water is safe to drink from the tap unless the cruise ship authorities say otherwise. The water onboard a cruise ship is desalinated, filtered, and chlorinated to meet the standards of the World Health Organization and U.S. public health recommendations.

The water from fountains and portable water bottle refill stations generally tastes better than water from the tap because it’s filtered for a second time.

The ice cubes on the ship are made from the same purified water that you drink. So you won’t need to worry about the safety of drinking water with ice cubes.

Do Cruise Ship Pools Fresh Water?

Pool deck of the Norwegian Cruise Line Pearl

Most cruise ship pools use treated seawater rather than saltwater.

The cruise line filters and chlorinates seawater, so it’s safe to swim in but should not be consumed. Many first-time cruisers are shocked that the pools are filled with saltwater. But don’t worry, it is treated and safe to swim.

Though saltwater pools are the more common, many new cruise ships have freshwater swimming pools. The trend towards freshwater pools may be for passenger comfort, but it’s also a sign that clean water is becoming easier to produce.

How Many Gallons of Water Does a Cruise Ship Hold?

The amount of water a cruise ship can hold varies depending on the size of the vessel. Most cruise ships store between 500,000 to 750,000 gallons of water. But it may be higher or lower depending on the cruise ship’s size.

Although ships make their own freshwater onboard, the freshwater generators can’t operate in the port. That’s because the water intake can become polluted in shallow waters like ports and shallow passages.

Steam evaporation systems can only be turned on when the ship is at least four nautical miles from shore, and reverse osmosis plants need a minimum depth of 50 meters to operate.

Cruise ship water storage is essential for a vessel’s long hours in port. During that time, water storage might be the only source of freshwater.

Do Cruise Ships Use Recycled Toilet Water as Drinking Water?

Close up of a passenger filling a glass of water from a cabin bathroom sink
recruit filtered water in a glass

No. Wastewater, including toilet water, is separated, not recycled, into drinking water.

Black water from toilets and grey water from showers and sinks are processed and discharged into the ocean following local laws and the International Maritime Organization.

Cruise lines claim that wastewater is treated to make it safe enough for consumption; however, it is never used as drinking water.

Carnival Cruise Line recently added bio-digesters to its onboard wastewater treatment facilities. The process uses microorganisms, oxygen, and warm water to break down 99% of the food and organic material in wastewater, making it safe to discharge into the environment.

Can I Use Cruise Ship Water for Baby Formula?

Cruise ship water is generally safe for mixing with baby formula. It’s important to consider that the water on a cruise ship may be treated with chlorine or bromine, which can cause an upset stomach for your infant.

Out of an abundance of caution, it’s recommended to use bottled water for baby formula. Most cruise lines allow guests to bring bottled water on a cruise ship for infant formula. Even if the cruise line doesn’t explicitly state that bottled water is allowed, you can contact the cruise line and ask for an exception.

If you don’t have bottled water, it can be purchased onboard through your drink package or onboard spending account.

Adding a portable water bottle to your packing list is a good idea to take fresh water into port.

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Author

Marcello De Lio

I’ve been cruising since I was 11 years old. I love the freedom that cruising provides, meeting new people, and exploring amazing new ships. I love to share my passion for cruising and travel with readers.

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