Where does the water on cruise ships come from?
IT sprays out of the showers, fills the pools and is used in the kitchens to prepare meals. Over a million litres of water can be used on a cruise ship every day. But where does it come from?
Essentially, it all starts out as seawater, according to one major shipbuilding company.
First, water is pumped into the ship and the salt is removed using special systems such as reverse osmosis machines and vacuum evaporators. At this point, the water is still essentially a distillate and not yet drinkable.
Next, it has to be mineralized — instilled with various substances such as calcium. Only then, according to Meyer Werft, does it achieve the standard of normal drinking water. Finally, the water is disinfected with chlorine.
The finished product is stored in tanks in the ship’s hull and transported by pumps to the various locations where it is needed. The tanks are constructed in a way that prevents the water from becoming contaminated again.
Daily circulation in each tank and regular checks help to ensure the water remains high quality drinking water.
It is possible to fill the tanks with fresh water on land. But this does not happen very often: “In general, ship owners prefer to use self-produced water because these measures help to ensure consistently high quality,” says Peter Hackman of the Meyer Werft shipbuilding company.
At the same time, water quality simply does not live up to the required standards in many countries.
On cruise ships, there’s no such thing as industrial water. The showers, pools, kitchens and even the toilets are supplied mainly with fresh drinking water.
Some wastewater, for example from air-conditioning units, is used to do the laundry. But all wastewater is generally chemically and biologically treated before it is brought back into use.
Meyer Werft estimates that its customers consume between 200 and 250 litres of drinking water a day.
But that is something of a miscalculation, because it doesn’t take into account water used for the kitchens, pools and cleaning the ship, for example.
All in all, a cruise ship carrying 6,000 customers can use up to 1.2 million litres of water a day.