great excersice!

i don't know exactly what type of sickness it is but usually when i swim in public pools so far the only negative thing i get is dry skin and hair. swimming is a healthy exercise and it really helps especially if you have asthma. i had asthma when i was in grade school and my doctor recommended swimming. my asthma may not have been cured completely but i never had an asthma attack for years. about the pool, you can check and ask around first if some people who swim in the pool had illnesses from swimming in it. you can also ask the caretaker(or who ever treats the pool) how they treat it so you know whats in it.

you can get athletes foot fungus from the showers and bathroom floors. Try to wear swim shoes when using a public pool

I think public pools are fairly safe. But be careful in lakes. If you snort the water, you can get an amoeba in your brain, which is fatal. Wearing a nose plug will protect you.