Clean in the pool

Have a shower BEFORE getting into the water, too!

The use of chlorine or related substances to disinfect swimming pool water is among the best-known chlorine applications. Chlorine is effective, inexpensive and safe to apply. Swimmers appreciate the fact that they can sport or relax knowing they get optimal protection from germs. Yes, chlorine really does the trick.

If only there weren't those occasions when after a while the eyes, lungs and skin got quite irritated. Then people start to wonder. Wasn't there a bit too much chlorine in the water? Shouldn't I have got out of the water sooner? Was the water clean enough? And why is this discomfort greater in indoor than in outdoor pools?

Justified questions. Let us look for answers and peek into the chemistry of the swimming pool.

You may know that chlorine is a very reactive molecule. This is precisely the reason why it is added to swimming pool water: the chlorine reacts with the proteins of bacteria's cell walls, breaking them down and destroying the bacteria. The pool water is now effectively disinfected from potentially harmful germs. But, since chlorine is so reactive, it may also react with other substances than germ proteins in the pool.

Perhaps unexpectedly, the typical smell of swimming pools is NOT chlorine. It is due to substances we call chloramines. Where do these come from? Well, it is a fact that pool water may also contain impurities like human perspiration, urine and oils. The chlorine reacts with these unwanted substances to form chloramines. More volatile chloramines will spread in the pool air and may cause the described irritations.

You may now conclude that proper ventilation is the solution to this problem, and you are right. But you also appreciate a cosy warm swimming pool, so the pool management will probably not open all possible windows to get rid of the chloramines. The energy that powers the heating system is expensive, thus a proper balance between heating and ventilation will be a fair objective. By the way, outdoor pools are by definition well ventilated, so here the chloramine irritation will be much lower.

So what else can we do? It's quite simple: avoid unwanted dirt getting into the pool water. Let's all have a good soapy shower BEFORE getting into the pool. Also, avoid peeing in the water and encourage kids to have regular bathroom visits. Do not swim when you have diarrhoea. In other words: let's all keep the pool cleaner. And enjoy a healthy swim!

Read more about chlorine and swimming pools on our Swimming pools page.