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Prevent Waterborne Illness in your Spa or Hot Tub


rwi-in-hot-tubs“Recreational Water Illness” is a term used to describe the effects of different pathogens that can survive and thrive in pools and spas.

According to the CDC, “Recreational water illnesses (RWI’s) are caused by germs spread by swallowing, breathing in mists or aerosols of, or having contact with contaminated water in swimming pools, hot tubs, water parks, water play areas, interactive fountains, lakes, rivers, or oceans”.

Of course, in this discussion, I’ll focus on preventing RWI’s in hot tubs and spas.



The two largest Recreational Water Illnesses that we see in poorly maintained spas and hot tubs are Pseudomonas and Cryptosporidium. The first is a form of dermatitis, or skin inflammation (a rash), and the second is a germ that causes diarrhea.

Pseudomonas Aeruginosa

Pseudomonas is sometimes referred to as “Hot Tub Rash”, although I don’t particularly like that term! It is a form of bacterium that is present everywhere in nature. It is naturally occurring in soil, air and in all bodies of water. It produces a red rash, with small dots to the size of a pea, which resemble chicken pox. Hot tub folliculitis can be painful and is quite itchy, similar to poison ivy. The rash usually lasts about 7 to 10 days, but can leave marks on the skin for several months. Antibiotics and ointments may be prescribed in some cases. The extent of the rash depends on the length of exposure; those who soak longer in an infected tub may display more acute symptoms.


Crypto, as it’s known for short, is one of the most common Recreational Water Illnesses, and is spread through Fecal matter. It has a hard outer shell that makes it incredibly resistant to environmental factors, including chlorination. It can survive days in chlorinated water, until a sufficient oxidation potential is reached with bromine and/or ozone treatment. Crypto can remain in the lower intestine for up to five weeks, and can be transmitted from the feces of an infected person to a new host.


For most of you reading this, you’ll never have to worry yourself about these germs and bacteria in your home hot tub. Public pool and spas, with large bather loads are the more likely place you can pick up one of these water illnesses.

With spas and hot tubs, we filter, circulate and treat with sanitizer, to prevent bacterial colonies from forming. Let me say that again – In hot tubs, we control Pseudomonas and other germs – with proper Filtration, Circulation and Sanitation. RWI’s only survive and thrive in poorly maintained spas and hot tubs.

I should also say that Crypto, in particular, is primarily released in the spa from users that don’t shower thoroughly before using the spa. We all know, toilet paper doesn’t get everything – and if you go into the spa with a dirty behind, and you are infected, you will release the germs into the hot tub. The germs can be absorbed by others by water that gets into their mouth, nose or eyes, or even through small cuts on the skin.

Adding an additional form of spa sanitation, such as ozone or mineral sanitizers, can aid your primary sanitizer (Bromine or Chlorine, or Biguanides) in fending off the onslaught of bacteria that escalates quickly when several adults get into the tub, and the sanitizer level takes a nose dive.

Protect Your Spa

  1. Keep a constant residual of sanitizer in the tub, at a high enough level to control Pseudomonas. Chlorine – 2-4 ppm, Bromine – 4-6 ppm.
  2. Limit guests to 30 minutes per soak, and no more than the recommended user load. Shock the spa after use, or at least twice per month.
  3. Drain and Refill your hot tub every 3 months, or 30 uses, whichever comes first.
  4. Filter your Spa continuously and effectively. It should never stagnate longer than a few hours.
  5. Clean your spa filter regularly, and replace the cartridge every 12-24 months.

Protect Yourself & Others

  1. Take hot showers before using the spa, being sure to wash “thoroughly”.
  2. Don’t drink the water! Remember “Montezuma’s Revenge?” Same thing.
  3. Shower after using a public pool or spa, and remove wet swim clothes.
  4. Don’t use a pool or spa if the water quality looks questionable, or there are too many users.
  5. Don’t use a pool or spa if you have had diarrhea in the last two weeks.

You can prevent Recreational Water Illnesses by following the tips above, in your own spa, and in your water activities outside of the home. Have questions? Leave a comment below.

Happy Hot Tubbin’

Daniel Lara
Hot Tub Works


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