This post is sponsored by Henson Shaving! Their single-blade razors are made of aerospace grade aluminum and are designed to give you the closest shave ever. Get 100 blades free with code MYSWIMPRO. Shop now >

We know most people pee in the pool, we just don’t know how much…If you’ve ever wondered just how gross your pool is, read on to find out!

We did the math to determine just how much urine is in a hot tub, a small pool and an Olympic-sized swimming pool. 

How to Measure the Amount of Pee in a Swimming Pool

To find out how much pee is in a pool, we need to take a scientific approach. 

We’ll take a water sample and determine the amount of artificial sweetener in it, specifically acesulfame potassium. This sweetener is in a lot of the food we eat, and because our bodies can’t break it down, we end up peeing it out.

Using a liquid chromatography instrument called a mass spectrometer, we can detect acesulfame potassium molecules in our water sample. Based on these results, we can extrapolate to figure out how much pee is in the entire pool.

For an in-depth breakdown of all of these calculations, check out Mark Rober’s video on YouTube.

Why Chlorine is in the Pool

You might be wondering…if there’s still pee in the pool, does chlorine actually do anything? The short answer is yes.

Chlorine breaks down harmful bacteria in the water that can make you sick, and keeps the water clean.

Related: What Chlorine Does to Your Body When You Swim

But when we pee in the pool, chlorine reacts to our urine to create trichloramine, which is what causes the chlorine smell that so many pools have. This reaction is also responsible for eye irritation and redness, and even some breathing issues people experience at the pool.

So, now you know…if your pool smells like chlorine, lots of people are peeing in it. Pretty gross, huh?

Calculating How Much Pee is in Your  Pool

If you’re curious to know how much urine is in your pool, we calculated a few averages for pools of different sizes:

Hot Tub

  • 103 nanograms of pee per liter of water
  • 1 gallon of pee

Small Recreational Pool (Backyard or Community Pool)

  • 470 nanograms of pee per liter of water
  • 13 gallons of pee

Olympic-Sized Pool (50m)

  • 100+ gallons of pee

How to Calculate the Amount of Pee in Your Pool

Swimmers introduce an average of 25-80 milliliters of urine into the pool per swim workout. To calculate how much pee is in the pool, use the following equation:

# of Swimmers in the Pool Per Day X 1.2 = # of Gallons of Pee in the Pool

Let’s see how much pee a 200-person swim team would introduce to an Olympic-sized pool.  

Since swimmers are in the pool for hours at a time (much longer than the average person), they might pee even more than the average, so we’re going to increase our 1.2 constant variable to 1.5. 

200 swimmers X 1.5  = 300 Gallons of Pee

The average Olympic-sized pool contains about 600,000 gallons of water or more, which means the pool has a 0.05% concentration of pee. That’s about one part per 2,000. 

If the pool is well-maintained, the water will be clean and free of harmful bacteria. But you’ll still experience a bit of eye irritation from the trichloramine. 

Related: How Many Swimming Laps are in One Mile?

Don’t let this information deter you from going for a swim in a public pool. It’s perfectly safe to swim in a pool that has pee in it. If you’re grossed out, don’t add to the mix and avoid peeing in the pool yourself. Head to the bathroom instead! 

To protect your skin from irritation and keep it soft between swims, check out Henson Shaving. Their razors are designed to give you the most precise shave ever, with a single blade positioned at the optional shaving angle.

Plus, every Henson razor is made of aerospace grade aluminum, which will last a lifetime. Use code MYSWIMPRO to get 100 free razor blades with your Henson Shaving purchase.

Let us know what you think in the comments! Do you pee in the pool?



  1. I never, ever pee in the pool. Seems like something only kids would do. Glad my pool never stinks – makes me feel even more respect for my fellow swimmers!

  2. When you started out the article by saying “we know most people pee in the pool” I was so shocked and grossed out. I would say, “we know most people pee in the lake or ocean”, but surely not the pool. Is it seriously a normal standard thing for specifically lane swimmers to pee in pools? If so, that’s pretty gnarly, just go to the washroom that’s right beside the pool! It just seems childish for specifically adults to intentionally pee in a pool. I grew up with a pool and guys would often get out and pee in a bush and the ladies ran to my house. I find it hard to believe or at least accept that people intentionally pee in pools. 😭

    • I get out of the pool to pee, but have often lost my swim lane as a result. People seem not to understand that if you swimming a mile or more, you may need to get out of the pool for a minute to pee. I even leave my stuff by my lane and come right back. And yet people take my lane. Maybe others don’t want to chance having their lane taken.

  3. The statement about the chlorine smell in the article being caused by “pee” is nonsense, I’m afraid. It may ALSO be caused by “pee” but certainly not SOLELY. I just filled up my hot tub and added the normal required amount of chlorine, in its different forms. The smell of fresh chlorine was, as usual, very evident and absolutely zero to do with “pee”. Relax people. I expect the author has unscientifically failed to take account of the differing forms of chlorine that build up and are regularly tested for…, once initially added to the water – but it makes for a “good read”…..😆😆

  4. I do not agree that there is a chlorine smell in a pool because it is the smell caused from urine mixing with chlorine. When you use bleach in your wash it can have a chlorine smell and there is no urine in the wash. A bottle of Bleach itself has a strong odor no urine in there either. Also, I agree with the other comments..I do not ever pee in the pool or hot tub….ever, Out of respect for myself and others.

  5. Elliot Ratchik on

    I am a Chemist and would like to explain why you smell chlorine in a pool environment.
    1. Chlorine is only slightly soluble in water and its solubility depends on the water temperature ( 0.3 % to 0.7 % and a maximum solubility at 49 deg C.) in the pool it forms HOCl.

    2. Keep swimming!

  6. I agree with the other commenters, I think it’s ridiculous for you to say that “most people pee in the pool.”

  7. It’s not just pee that makes Chloramines. Body oil, sweat, lotions, fecal matter – anything with Nitrogen in it – makes these nasty compounds. A good air handling system will take most of them away as they sit right over the water for a time before disolving back. Air returns at deck level facilitate this. I’m a CPO anjd currently manage 3 pools year round and 4 in the summer.

Leave A Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.