Having too much chlorine in your pool water can be dangerous. Exposure to high levels of chlorine can cause lung irritation, skin and eye damage, and provoke asthma. Not only is it bad for your health, but it can be bad for your pool due to the increase in chlorine.
What chlorine level is too high to swim? It depends on who you ask, but the acceptable range is between 1 to 5 ppm. (So, for example, 10 ppm chlorine is not safe to swim in — that's too high.)
The surrounding environment dictates how long it takes for the chlorine to evaporate. Warmer air will cause the chlorine to evaporate more rapidly. If you decide to place the water in a jug that's left open in the refrigerator, the chlorine should evaporate completely within 24 hours.
Two different chemical agents that can reduce chlorine levels are Sodium Thiosulfate and Pool-Grade Hydrogen Peroxide (specific to pool treatment). Be sure to test your water after using one of these agents as they tend to impact pH, sometimes dramatically.
But excessive exposure to chlorine can cause sickness and injuries, including rashes, coughing, nose or throat pain, eye irritation and bouts of asthma, health experts warn. Instructions for safely chlorinating a pool usually call for a maximum of four parts per million when people are in the pool.
The bottom line: We're vastly better off having pool chemicals than not, and chemically treated pools are generally safe to swim in, especially if they are well maintained and ventilated. Add to that some time-honored advice that probably bears repeating: Don't pee in the pool.
If you enter the pool immediately following a chlorine pool shock treatment, you are risking as little as skin and eye irritation and as much as fatality. Shocking your swimming pool is necessary, but take caution when doing so.
And how long do you have to wait before you can swim? You should wait one hour per pound of shock product added, and then test the water to confirm the pH and chlorine are in the proper range before letting anyone enter the pool.
After you shock the pool — As soon as your chlorine levels reach 5 ppm or lower, it's officially safe to swim. Depending on the type of shock used, as well as the amount used, it can take anywhere from 24 hours or even up to a couple of days.
Best Time to Shock Your Pool
The best time of day to shock pool is when the sun is down. So, experts recommend shocking your pool in the evening or at night, to make sure it does its job. Shocking during the day can be ineffective as UV rays from direct sunlight significantly reduce free chlorine levels.
The Bottom Line about Pools and Chlorine
As mentioned above, you could probably swim in a pool without chlorine without any major health issues. However, long-term use of a pool lacking chlorinated H2O could make you sick or, at the very least, contribute to rashes and other types of skin irritation.
If used properly, free chlorine* can kill most germs within a few minutes. CDC recommends pH 7.2–7.8 and a free chlorine concentration of at least 1 ppm in pools and at least 3 ppm in hot tubs/spas.
Yes, boiling water for 15 minutes is one way to release all the chlorine from tap water. At room temperature, chlorine gas weighs less than air and will naturally evaporate off without boiling. Heating up water to a boil will speed up the chlorine removal process.
You can swim with chlorine tablets in the pool if the chlorine tablets are in a container. Getting in touch with those tablets can cause rashes, irritation and eye problems. However, to be in a safe zone it will be better if you wait for 3 to 5 hours till the chlorine levels touch 4 to 6 ppm.
People who have aquariums or simply don't want to be exposed to chlorine in drinking water often look for ways to remove it. It will kill fish and is a toxic chemical. Letting water sit does remove chlorine. Chlorine is a gas that will evaporate from standing water if the air is warm enough.
How fast does chlorine evaporate from a pool? Just two hours of sunlight on a beautiful day can reduce the chlorine level in your pool by as much as 90 percent. That's why you see pool service technicians adding chlorine and stabilizers regularly. But, chlorine degradation in sunlight isn't your pool's only enemy.