Although there have been no cases of COVID-19 transmitting through pool water, the virus could certainly be present in the air or on the surfaces of an aquatics facility. And many other diseases do transmit through pool water.
This article discusses the nature of the coronavirus that causes COVID-19, as well as how to clean and disinfect to prevent its spread in a facility.
Coronavirus
The coronavirus, like all viruses, is not a living organism. It cannot be killed — it decays.
It is a single-strand ribonucleic acid (RNA), linear protein molecule (as compared to double stranded DNA), covered with a protective layer of nonpolar, hydrophobic lipids (fats) that do not dissolve in water. The virus mutates and multiplies when absorbed into the mucous membranes of your eyes, nose, or mouth. But this is actually difficult to do, because the function of the mucosa is to prevent dehydration of these bodily tissues and stop dirt and pathogens from entering the body.
The virus is more concentrated in confined spaces and needs moisture and darkness to remain stable. It is more durable in cold or air-conditioned indoor spaces, and more likely to degrade in dry, warm, bright, dehumidified environments.
It is not a living organism like bacteria or protozoa, so a bactericide will not kill it — you can’t kill something that isn’t alive. But soap and detergent foams dissolve the protective external fat/lipid layer, as will heat above 77° Fahrenheit, and ethyl alcohol with a greater than 70% concentration.
Chlorine compounds, hydrogen peroxide, ozone and ultraviolet light, particularly UVC, can be used to degrade or dissolve the RNA protein molecule. A solution of one part household bleach to five parts water will dissolve the RNA protein molecule from the inside. The World Health Organization (WHO) currently recommends using sodium hypochlorite at 0.5% / 5,000 ppm / 1:200 for disinfecting surfaces (1% equals 10,000 ppm).
The Centers for Disease Control and Prevention recommends that a freshly diluted 5.25-6.15% household bleach hypochlorite solution at a ratio of 1:100 be applied to an already cleaned surface to disinfect after small spills. Or mix a 1:200 solution if using 10-12% commercial grade sodium hypochlorite (liquid pool chlorine).
For large spills, use a 1:10 ratio followed by a 1:100 solution of household bleach; or 1:20 then 1:200 commercial sodium hypochlorite solution to disinfect. Let air dry. A 1-to-10-minute contact time is recommended.
Cleaning and Routine Maintenance
Operators should develop Standard Operating Procedures (SOP) to immediately destroy germs in pool water, in the air or on surrounding surfaces.
Aquatics facilities should have a written chemical treatment, cleaning and routine maintenance plan to prevent pathogens from becoming a problem in the first place. Checklists should be completed daily, with items checked off by the person who actually completed the task, and only after a task is completed. The checklist should be reviewed by a supervisor. After inspection, to verify satisfactory completion, the supervisor should sign the checklist indicating the facility is ready.
The facility should be spotless. Tidy up. Pick-up and dispose of trash, move items left by patrons to the lost-and-found, and return items to where they belong.
Next, clean the facility. Cleaning means to physically eliminate dirt, debris, spills, soiled areas, organic (living fats, lipids, proteins, enzymes) and inorganic (non-living salts, elemental compounds and solids) matter. It is necessary to clean before disinfecting, as some germs may be protected by residue. For example, bacteria being harbored by algae or slimy biofilms, or viruses by lipids.
Clean using friction and soap and water, detergents, enzymes, or trisodium phosphate (TSP). Or do this mechanically by using a machine such as a power scrubber or pressure washer.
Some interesting facts about soap versus detergent: Soaps are produced from natural ingredients such as fats and oils from plants. Detergents are synthetic, man-made cleaning products that mix with dirt and other impurities to make them better able to dissolve in water. Scum or insoluble precipitates don’t form when detergents combine with salts and minerals in hard water when detergents are used instead of soap.
TSP used to be added to detergents to soften the water and make them foam better, but manufacturers have removed it from many products due to environmental impact concerns (algae growth and reduced oxygen levels in lake water). As a result, dishes and laundry are not as clean. However, TSP is still widely available as a stand-alone product and commonly used for cleaning in facilities. Use a diluted 1:20 solution for general cleaning, or a 1:10 ratio for stubborn stains. With all cleaning products, apply, soak, scrub, then rinse thoroughly to remove residue so it doesn’t interfere with disinfection.
The next step
After cleaning, then disinfect.
This process kills or inactivates pathogens (disease causing organisms). Disinfection is not the same as sterilization, which kills or eliminates all biological organisms — harmful or beneficial — by physical or chemical means. When disinfection inactivates a pathogen, the replication and spread of the germ is prevented.
Steam will disinfect, as will alcohol, many commercially available disinfectant products, biocides, chlorine compounds and other halogens, ozone, and ultraviolet light (particularly UVC).
Don’t forget to clean and disinfect both vertical and horizontal surfaces. In addition to floors, decks and walls, include benches and all seating; rides and attraction surfaces; slide transport media such as inner tubes, rafts, mats; wet suits, goggles, masks, fins and snorkels; racing lane lines; rescue equipment such as back boards and rescue tubes; kickboards; instructional equipment; and items used by more than one patron or employee.
When cleaning and disinfecting are complete, launder or properly disinfect cleaning equipment including brushes, brooms, buckets, skimmer nets, towels and rags before putting them away.
Always check to make sure cleaning and disinfecting products used for cleaning and disinfecting are compatible with pool water and do not create any unwanted side effects.
Follow the manufacturer’s instructions on storage, disposal, dilution, spill containment and compatibility.
