You might think swimming pools are just a simple mix of blue water & chlorine. But you’d be wrong. There’s a lot more going on with pools than meets the eye, including some strange chemistry and weird biology.
Here are seven interesting facts about swimming pools. Which one surprised you the most?
Urine really does react with chlorine
Pool smell doesn’t come solely from chlorine. It’s actually from when urine mixes with chlorine to create gases like cyanogen chloride & trichloramine, both of which irritate your eyes and nose.
Tiny amounts of uric acid trigger this chemical reaction. So yes, your eyes stinging after swimming is caused by chemistry, rather than cleanliness.
Scientists measured how much urine is actually in pools
Speaking of urine, scientists performed tests to see how much urine is in pool water. They checked for a sugar substitute known as acesulfame-K, which passes through the body unchanged. What did they find?
It was in every pool they tested. The scientists compared levels & found out that a public pool likely has around 30 to 75 liters of urine. How delightful.
Swimmers add sweat
Most people have no clue about how much they’re actually “contributing” to pool water. Each swimmer adds sweat & plenty of other organic material to the swimming pool, even when they don’t leave the lane.
The average person releases around 0.1 to 0.8 liters of sweat every hour. That’s not including other compounds like nitrogen & carbon. These all mix together in the pool, making for a shared experience in the worst way.
The water looks blue because red light gets absorbed
Physics is the reason why pools look blue, not dye or tiles. Water naturally absorbs red light better than blue. The light that bounces back to your eyes looks sky blue, and the deeper the pool, the more blue it appears to your eyes.
It’s the same reason a glass of water looks clearer than an Olympic pool.
Green hair from pools comes from copper, not chlorine
That’s not all for colors. Most people assume that when their hair goes green after swimming, it must mean there’s a high concentration of chlorine in the pool. But the real cause is copper.
Copper leaches from pipes & algaecides, then grabs onto your hair protein. The effect is especially noticeable with blond or color-treated hair.
Thankfully, you can avoid the effect by rinsing your hair first or using special shampoos to take the metal out.
Olympic pools are kept colder on purpose
Olympic swimming pools are cooler than you might expect. Officials keep the temperature around 77 to 82°F. Why?
Because it’s the perfect temperature for when you’re trying to move quickly, as cooler water helps your muscles work longer. The lower temperature also keeps your body temperature steady when you’re doing intense laps.
The world’s deepest pool could swallow a building
Poland is home to the world’s deepest swimming pool. It’s called Deepspot & it has a drop of approximately 148 feet. That’s rather impressive when you remember that the average building is only around 20 to 26 feet, including the roof.
Deepspot also holds a million gallons of water. But the pool isn’t made for a casual swim. It’s only for divers & film crews, as well as those who are training to deal with pressure under deep water.
The following sources were consulted in the preparation of this article:
- Volatile disinfection byproducts resulting from chlorination of uric acid: implications for swimming pools
- Quantification of continual anthropogenic pollutants released in swimming pools
- Absorption spectrum (340–640 nm) of pure water. I. Photothermal measurements
- Sweetened Swimming Pools and Hot Tubs
- Pseudo Green Hair
- Deepspot – a pool of extraordinary transparency
- FINA facilities rules 2021 – 2025
