SARS-CoV-2 And Your Pool: What’s Real, What’s Rumor, What to Do To Keep The Water Safe.

Over the past 6 months, much of the world’s focus has been increasingly fixated on the outbreak and spread of the SARS-CoV-2 coronavirus, everything from where it came from, how it spreads, how contagious/dangerous it is, to when will an effective vaccine and course of treatment be available. This article leaves those questions and debates to others, since all we’re concerned with here is (1) what does this virus mean to pool owners and operators, and (2) how should we be dealing with it in terms of water quality? Let’s get right to what we know.

What’s Real?

Free Chlorine Can Inactivate and Kill the Coronavirus. Even though we are not aware of any specific studies on swimming pools and this latest strain of coronavirus, there has been laboratory testing that proves contact with free chlorine will, at a minimum, inactivate this virus, and at the correct levels, kill it. That’s great news, since most residential pool owners use (and we think should be using) chlorine as their primary sanitation/disinfection agent to kill waterborne pathogens. In later posts, we will address the options to provide supplemental disinfection equipment, as well as best practices for operating pool pumps and associated equipment to maximize their benefits.

So what is “free chlorine”? In the simplest terms, it is dissolved chlorine in the pool water that has not already combined with other impurities (such as urine, body oils, cosmetic products, etc.) so that is it “free” to react with and de-activate/destroy germs and pathogens in the water.

What’s Rumor?

So Long As I’m Putting Chlorine in the Water, I’m Fine. Too many people simply test the total chlorine level in the water, and think that’s all they need to know. Wrong! The total chlorine level is the combination of free chlorine and “combined chlorine”, which is chlorine that has already bonded to impurities, and can no longer effectively act as a sanitizer/disinfectant. Looking only at the total chlorine level can give you a false sense of security in how effective the chlorine in your pool is working to keep swimmers safe. Keeping a sufficient level of free chlorine (at least 1 part per million, or 1/ppm, is recommended by the CDC) is essential for maintaining proper water quality to deal with the coronavirus and other pathogens.

What Should I Do to Keep The Pool Water Safe?

Test the Pool/Spa Water Regularly. In our opinion, this is the most important step. You can’t look at the pool water and tell whether you have enough free chlorine to properly sanitize and disinfect. The testing frequency interval depends on a number of factors, including the level of bather usage, the water temperature, the amount of sun your pool gets, etc, but you should be testing no less frequently that once every few days in the summer. We can test or you can test on your own. There are residential test kits that test for free chlorine, the better test kits have separate reagent bottles and require more care. AquaCheck has a good test strip that tests for both free chlorine and total chlorine (check the label for the expiration date), but it’s a good idea to get more accurate testing at least once a month.

When the Combined Chlorine Gets High, It’s Time to Super-chlorinate, or “Shock” the Pool. This step completes the removal of the contaminants in the combined chlorine, using a finely powered form of chlorine without stabilizer to temporarily raise the chlorine to a very high level before lowering back down to the prior levels, usually within 24 hours. These products are available at your local pool supply stores. How much to use depends upon the gallons of water in your pool or spa, and the shock products will indicate the correct dosage based on the volume of water in the pool or spa.

Protect Your Free Chlorine with Stabilizer. Lots of sunlight and higher water temperatures (above 80°F) each act to reduce the level and effectiveness of the free chlorine in your pool. Adding pool stabilizers can limit the impact of the UV rays from the sun on the free chlorine. There are a number of good stabilizer products on the market for just this purpose, such as Natural Chemistry’s Instant Pool Water Conditioner, which is a liquid that is added to the pool, the dosing directions are on the label.

Reduce the Contaminants Entering the Pool. We realize this is easier said than done, but where possible, it will help maintain the levels of free chlorine. These simple steps include:

  • Rinse your body off before going in the pool.

  • Remind bathers not to urinate in the pool.

  • Anyone with an open wound should cover it with a waterproof bandage.

  • Anyone who has diarrhea, or has had diarrhea in the past 2 weeks, should not be in the pool (cryptosporidium, a fecal parasite, can live in pool water treated with only chlorine for days).

The information provided in this article is intended to inform you about some of the basic steps to take in minimizing the risks associated with SARS-CoV-2 in terms of water quality. This does not mean, however, that maintaining good water quality will prevent bathers from contracting or spreading the coronavirus, particularly if someone comes in close proximity to someone who is contagious. The CDC has some good recommendations on safe swimming practices, check out their website on this topic.