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PHTA on how to decontaminate spas

PHTA on how to decontaminate spas PHTA on how to decontaminate spas

There are specific conditions that exist within a spa that can pose a threat to bather health if the water, shell, plumbing and filtration systems are not adequately maintained after contamination. Typical indications of contamination requiring remediation include slime formation, cloudy water, musty odors, vomit or fecal contamination. These conditions can result in threats to bather health which can include rashes, flu-like symptoms, diarrhea or respiratory distress and may have originated from contact or swallowing contaminated water during use. Many of these symptoms may take several days to develop.

If the user/operator suspects contamination, the procedure presented here can be used as a precaution. If the water is contaminated then the plumbing system and filter is likely to be harboring bacteria, viral particles and/or parasitic pathogens that should be addressed. Therefore, the replacement of water alone is not sufficient. The vessel shell and its filtration/circulation systems should be thoroughly decontaminated as well.


1. Decontaminate water, filter, plumbing.

2. Drain, sanitize vessel, filter, plumbing then continue with water and/or filter media replacement and/or treatment.

3. Complete required documentation in cases involving an Accidental Fecal Release (AFR) accident or suspected bacterial outbreak or when decontamination is part of a general water replacement routine.

4. Appropriate Personal Protective Equipment (PPE) should be worn by operators during the decontamination process. See Precautions section for more information.

Clean the Filters Cartridge Filters: First, remove the filter cartridge and either clean or replace it. To clean a cartridge, first use a filter cleaner per label directions. After thoroughly rinsing the cartridge, completely submerge the cartridge in a 1:10 solution of sodium hypochlorite (liquid bleach) to water for one to four hours. Next, inspect and clean the filter-housing interior and all surfaces where possible using a 1:10 solution of sodium hypochlorite to water.

Diatomaceous Earth (DE) Filters:

First, backwash filters removing all DE housing and grids. Dispose of DE according to local regulatory guidelines. If guidelines do not exist, use CDC standards for disposal. Wash the remaining DE from housing and all filter grids. Where possible, remove and submerge filter grids in a 1:10 solution of sodium hypochlorite (liquid bleach): water for one to four hours. Inspect and clean the filter housing interior using a 1:10 solution of sodium hypochlorite. Water. Install filter grids after spa decontamination is complete.

Backwash the filter thoroughly according to local regulatory guidelines. Remove and dispose of the sand filter media. When following the decontamination procedure (below) as part of normal spa maintenance, sand replacement may not be necessary. Draw down the water to the sand surface and inspect for cracks, mounds or signs of channeling. Check the filter laterals and diffuser to determine any damage. Replace as required.

Decontaminate the Shell and Plumbing

1. Raise the water level to ½ inch above the high-water mark of the spa.

2. For diarrheal discharge or suspected bacterial outbreak (e.g. Legionella, Pseudomonas) maintain 20 ppm free available chlorine and 7.5 pH.

3. For formed stool, maintain 10 ppm free available chlorine and 7.5 pH.

4. Circulate the water under diarrheal discharge conditions for 12.75 hours; for spas, ensure the jets are on maximum.

5. While the water is circulating under diarrheal discharge conditions, turn the aerator (blower) on for 30 seconds every 5 minutes for at least one hour. Spas with air injector (venturi) systems may require the pump alternating operation from on to off every 5 minutes to ensure the disinfection of the air lines.

6. Circulate the water under formed stool conditions for 4.5 – 5 minutes and ensure the jets are on maximum.

7. Stop the circulation in spas by turning the jets and aerator off.

8. Check local regulatory guidelines before draining, then drain vessel and rinse the sides during the process.

9. Clean the shell with a surface cleaner and rinse off surfaces to remove cleaner.

10. Remove any excess water and cleaner.

Water Replacement and Treatment

1. Refill the vessel with water.

2. Replace the filter with a cleaned, sanitized or new filter cartridge, fresh sand or DE.

3. Balance water and sanitize as required by state and local guidelines. In the absence of guidelines, use ANSI/ APSP or CDC Healthy Swimming recommendations. ANSI/APSP/ICC-6 2013 American National Standard for Residential Portable Spas and Swim Spas swimming/index.html4. C o m p l e t e required state and local documentation.

In the absence of required documentation, use CDC recommendations in cases involving an Accidental Fecal Release (AFR) accident.


To minimize exposure to potentially harmful pathogens and disinfection byproducts during the decontamination procedure, operators in the spa area should use the following Personal Protective Equipment (PPE): 1. Appropriate air purifying respirator; 2. Goggles/eye protection; 3. Gloves; and 4. Any other PPE required by the MSDS’s of products being used in the decontamination procedure.

Unicel Cartridge Filter

Hayward Sand Filter

Unicel D.E. Grids

Sand Filters:

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