Be warned right up front: When it comes to cruise ship pools, this story is either going to kinda gross you out or make you shrug and say, “Yeah, that makes sense.”
A recent study by the University of Alberta concluded that the average public swimming pool contains about 20 gallons of urine.
The Good News For Cruise Ship Pools
Now, before you go shouting, “Ew, why would you tell us that?” know that this story has been reported by everyone from TV’s “The Doctors” to NPR. But here’s a bit of good news for you: The numbers cited above represented a commercial-sized pool containing about 220,000 gallons of water.
But here’s a bit of good news for you: The numbers cited above represented a commercial-sized pool containing about 220,000 gallons of water.
The typical cruise ship pool is smaller. And for the sake of comparison, the study showed that a residential pool measuring 20-by-40 feet and with an average depth of 5 feet — which seems more in keeping with the size of your standard cruise ship pool — only contains about 2 gallons of urine.
The study in question was looking at pools in landlocked locations such as resorts or public parks. The big difference where cruise ships pools are concerned is the frequency with which the water is changed. For example, Carnival Cruise Line’s website says that “the water is drained out and loaded a few times during the cruise.”
When this subject came up on the Quora forums a while back, Calvin Ung, a student of Environmental Earth Sciences & Physical Geography, provided info that should be downright comforting to cruise lovers. “In general,” he explained, “most cruise ships still use free-flowing seawater in their pools (the water is passed through a sand filter before it reaches the pool).”
Just The Facts
In fact, according to the guidelines from the Center For Disease Control — which does inspections of cruise ships as part of its Vessel Sanitation program — the water in the pools must be recirculated every 4-6 hours, depending on the type of pool/filtration system and what year it was built or installed.
On top of that, Ung added that “To keep the water quality high (given impurities [which] enter the pool from all the people swimming in it), the water is also completely dumped daily (usually in the early morning), the pool sanitized and subsequently refilled with seawater.”
The Bottom Line
What that means, essentially, is that the water in your typical cruise ship swimming pool is probably a whole lot cleaner than what you’ll find in your home pool, let alone the public one where your kids take swim lessons every day.
