How Long After Shocking a Pool Is It Safe to Swim? Here's What to Know

Why you can't just jump right into a newly opened pool, according to experts.

It's finally swimming season again, and that means pools everywhere are gearing up to help cool you (and plenty of other people) down. But pools aren't just magically ready to go when warm weather hits—they have to be prepped and shocked first.

Shocking is a crucial part of having a clean pool, but it involves the use of some pretty hefty chemicals, including chlorine. It's only natural to wonder when you can dive in after all of that.

Experts say you definitely shouldn't rush the process—here's why.

when it’s safe to go in your pool after shocking it
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OK, what is "shocking" a pool?

If you've been around pools, you've probably heard the term here and there, but you're not exactly born knowing the ins and outs of this stuff. Shocking is "the process of adding chemicals to the pool to make water composition ideal for chlorine or non-chlorine alternatives to work best," Jamie Alan, PhD, an associate professor of pharmacology and toxicology at Michigan State, tells Health.

The goal of shocking the pool is to raise the level of "free chlorine" in the pool to a point where things like algae and bacteria are destroyed. (Free chlorine is chlorine that hasn't yet neutralized harmful gunk in the pool.)

There is a range of chemicals that can be used for a pool shock, including calcium hypochlorite, lithium hypochlorite, dichlor, and potassium peroxymonosulfate, according to Home Depot.

When is it safe to go into a pool after it's shocked?

In general, it's recommended that you wait up to 24 hours to hop into a pool after it's been shocked, depending on the size of the pool, Alan says.

If you're overseeing the pool maintenance, Alan says it's also a good idea to test the water's pH and chlorine to make sure they're in the right range before you or anyone else gets in the pool. (A good chlorine level is between 1.0 and 4.0 parts per million, and the pH should be between 7.2 and 7.8, according to the Centers for Disease Control and Prevention.)

What can happen if you go into a pool too soon after it's been shocked?

There are a few potential issues. "Chlorine will react with water to produce an acid," Alan says. "The effects will be different depending on whether chlorine is inhaled or whether there is skin or eye contact."

At a minimum, "you would definitely get dry skin," Gary Goldenberg, MD, assistant clinical professor of dermatology at the Icahn School of Medicine at Mount Sinai in New York City, tells Health. And, if you happen to have a skin condition like eczema or psoriasis, Dr. Goldenberg says this could cause a flare. You may even deal with symptoms like burning, redness, pain, and blisters, Alan says.

But the water can also impact your eyes and lungs. "Eye effects would include pain, redness, blurred vision, and watery eyes," Alan says. "The inhalation effects are typically the most severe and include shortness of breath, chest tightness, wheezing, and fluid in the lungs."

And, if you happen to accidentally drink some pool water, you could end up feeling nauseous even throw up.

Luckily, Alan says, "the effects are typically reversible." If you hop into a pool too soon after it's been shocked and you start to notice symptoms, Alan says it's important to get out ASAP and get to fresh air (i.e. away from the pool). "Remove all exposed clothing and wash all the affected areas thoroughly with soap and water," she says. If you wear contacts, she also recommends taking them out, pitching them, and "thoroughly" rinsing your eyes with saline solution.

If your skin feels uncomfortable after you've cleaned off, Dr. Goldenberg recommends using a moisturizer and even a topical steroid cream if your symptoms don't improve. And, if you have trouble breathing, Alan says it's time to call 911.

It's tough to have to wait to hop into a pool, but it's definitely not worth messing with your health.

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