The Secrets Of How Cruise Ships Get Fresh Water When At Sea

Cruise ships can carry over 6,000 passengers – plus a full crew – all needing fresh water to drink and shower, plus the cooking and cleaning done by the crew. That’s tens of thousands of gallons, every single day.

So where does it all come from?

Spoiler: it’s not stored in giant tanks. That space is needed for fuel. The way cruise ships create fresh water is surprisingly efficient – and kind of fascinating.

Cruise Ships Make Their Own Fresh Water!

Cruise ships make their own drinking water. It’s unsurprising since they’re constantly surrounded by sea water – they use either steam evaporation or reverse osmosis processes to desalinate the water before minerals and chlorine are added.

It’s the same as a home filtration system, only much, much larger.

Cruise ships do have large stores for bringing water onto the ship at port, but there’s still nowhere near enough space to store all the drinking water needed for a cruise. Not if you also want to eat, anyway.

And since it’s easier to create drinking water than it is to source food in the middle of the ocean, food storage is prioritised.

The minerals added to the desalinated water are for flavour, while chlorine is a cleaning agent which will kill any unwanted bacteria. Don’t worry, it won’t taste like pool water, it’s a much lower amount – the same that would be in typical tap water.

The water from dispensers generally tastes better than the tap water in your cabin. That’s because it’s filtered a second time and cooled to a more pleasant temperature for drinking.

There Is Still A Lot Of Storage For Water

Cruise ships tend to be able to store around 500,000 gallons of fresh water in massive tanks in the hold. Once it’s been used by passengers for laundry, showering or in the toilet, it’ll be treated before it’s released into the ocean.

Ships make take fresh water on board at ports, but this isn’t suitable for drinking, and instead is limited for use in laundry, cooling the engines or as ballast. The drinking water tends to only be taken from the seawater that undergoes desalination.

River cruise ships tend to have much smaller water stores, and so need to top up their fresh water supplies at each port. This is less of an issue since they don’t usually go for days in between each port.

Cruise Water Cleanliness

Cruise ship water is generally very clean. It goes through intensive filtration processes to make sure it is safe to use. And there are rules about water recycling – water that has been used won’t be re-used for passengers on the ship.

Instead, used water is separated into grey water (laundry and showers) and black water (toilet) before being treated appropriately.

It then gets released into the oceans after it has been rendered safe, which must be done at a safe distance from land as dictated by the International Maritime Organization.

Tap Water Is Safe To Drink Onboard

Unless you are told otherwise, cruise ship tap water is safe for drinking. It is heavily filtered and chlorinated to an appropriate level to remove any toxins, with minerals added to make it taste a lot more pleasant too.

Some ship engineers have even supposedly described the drinking water on cruise ships as being healthier than bottled water. While that’s anecdotal, you shouldn’t be concerned about drinking the tap water unless you’ve been told that there’s a temporary problem.

This is good since bottled water tends to cost extra on a cruise, unless you have a drink package.

Some cruise lines let you bring your own bottled water on board. Some specify that it must be in cans or cartons (no plastic or glass) and others ban you from bringing water altogether. To find out which category yours falls into, read this guide to bringing bottled water on a cruise.

You should avoid drinking the water in the shower though – that’s good life advice, not just on a cruise ship.

A couple of other points worth mentioning – firstly, the ice on board is made using the same drinking water that’s been through the same processes. It’s handled carefully to the same standards as any food on board.

So, even if you don’t intend to drink the tap water, you can at least know that the ice cubes in your drink are also not going to cause you any harm. This is much better than many holiday resorts on land which use tap water to make ice, even when the tap water isn’t safe to drink.

Secondly, while the water on a cruise ship is safe for drinking, it might have a slightly different level of chlorine than tap water and so might not be suitable for baby formula. Also if you need distilled water for a medical reason, you should avoid tap water.

Suggested read: How to Feed Your Baby on a Cruise

Speak to your cruise line – they’ll have different policies on how much water you can bring on board if you have a specific need, and while they can always provide bottled water and usually they can source distilled water for you, it may be a paid-for extra. Some luxury ships may have it available for you free of charge.

Swimming Pool Water

Many cruise ship pools are filled with treated seawater. Chemicals are used to make sure it is clean and safe to swim in. Some ships will use fresh water and others will offer both – so you can see just how much more buoyant you are in a saltwater pool.

The trend seems to be that more modern cruise ships lean towards freshwater pools, which is probably a sign that the freshwater is easier to maintain and keep filtered.

The salt content of seawater will damage pumps over time, after all. And the modern larger ships have more storage space so they can filter in more fresh water than older ships would be able to.

Hot Water Systems Onboard

Cruise ships will have a robust hot water system on board to deliver the hot water around the ship where it is needed. Despite being a temporary home to thousands of passengers at once, it’s rare to see complaints about cold or low-pressured showers.

The fresh water that’s been desalinated will be fed into different plumbing systems throughout the ship for drinking, cooking and for showers and baths. It’s heated through the consumption of whatever fuel is used on the ship, before being pumped around each deck as required.

It’s not really any different to a typical domestic hot water system at home – just significantly larger and with a lot more plumbing involved.

To Conclude

It would be strange for a cruise ship to be surrounded by so much water and not try to take advantage, so you probably expected that ships used some sort of purification process to make sea water safe for drinking and washing. And now you know you were right.

You can wash in fresh clean water, your food will be prepared in safe water too, and you can feel comfortable drinking the tap water – if you aren’t too busy enjoying the soft drinks, cocktails and Champagnes, anyway.

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