Worried about wee in the pool?

We’ve all done it—a sneaky wee in the pool, secretly relaxing our muscles as we try to look completely innocent. Even when we're trying to be good, researchers at Purdue University in the United States have estimated that on average, each swimmer leaves behind between 50 and 80 millilitres (about a shot-glass full) of wee per swim. While it used to be thought that urine was sterile, it’s now known to contain bacteria.

However, it’s unlikely you’ll get sick from wee in swimming pool water because the bacteria in urine are likely to be highly susceptible to chlorine.

Wee in the pool can cause other problems however, due to how it reacts to chlorine in the water.

Chlorine is one of the most widely used sanitizers to keep pools germ free. When it's added to water, free chlorine is formed.  Free chlorine is the active disinfectant chemical form of chlorine, and does most of the work in killing bacteria and other germs.

When you ‘let it flow’ in the pool, your urine—which is composed of many different compounds— interacts with the chlorine in different ways.

For example, when the ammonia compounds in urine (known as amines) react to chlorine, free chlorine is used up. This contributes to the creation of chemical irritants called chloramines (combined chlorines). Certain bugs may flourish—or not be killed—because chloramines are not as effective as free chlorine in killing bacteria, and reduce the disinfection power of free chlorine.

Chloramines can also cause allergic or irritant reactions—if you’ve ever found yourself with streaming eyes or a runny nose at the pool, chloramines may be to blame. It is these that are often responsible for the strong 'chloriney' smell at public pools, rather than the chlorine itself. And if you plan on jumping in the pool after a run, perspiration can release amines into the pool too.

But it's not all bad news. Public pools have strict monitoring of water quality and advanced filtration and sanitation systems to keep swimmers healthy, but you can help too.

If you want to reduce the amount of chloramines in the water, then you'll need to keep the wee (and sweat) out of it. So pay attention to those signs and have a shower before swimming, leave the pool to urinate, and take any kids on frequent trips to the loo.

And whenever you swim, think of this: if you’re secretly weeing in the pool … there’s a high chance everyone else is too.