HealthLinkBC File #27b, March 2013
Residential Hot Tubs and Pools:
Safe Water Quality
- What are the health concerns of hot tubs and pools?
- How can I make sure the water is safe?
- How do I measure water disinfectants?
What are the health concerns of hot tub use?
Hot tubs and pools can provide a breeding ground for a number of bacteria that cause infection or disease. This includes the Legionella bacteria that cause Legionnaires' Disease, which can be fatal. As well, the Pseudomonas bacteria can cause a number of serious infections, such as severe skin rashes, eye and ear infections, and pneumonia. These bacteria can be easily controlled and removed by maintaining the disinfectant level of the water.
How can I make sure the water is safe?
You can prevent illness from hot tub and pool use by learning about and maintaining safe water quality in your hot tub. It is the owner's responsibility to ensure the hot tub or pool is clean and the water is properly disinfected to prevent the spread of germs and disease.
It is important to maintain the proper level of disinfectant to ensure clean and safe water in hot tubs and pools. Chlorine and bromine are the most commonly used disinfectants. Both chlorine and bromine kill viruses and bacteria. However, they also react with organic material in the water including: dirt, soap, shampoo, body oils, perspiration, food and drinks. The more hot tubs and pools are used, the faster the disinfectant in the water gets used.
Make sure to frequently check the level of chlorine or other disinfectants in the water, and add more if required. Also, make sure that you know the 'bather load' of the hot tub or pool (how many people can use the tub at a time), and do not allow more than its limit.
How do I measure water disinfectants?
The level of disinfectant in your hot tub or pool should be measured before and after use, or at least daily if not in use.
It is recommended that pool and hot tub owners get a test kit that can measure different types of disinfectants. Follow the instructions that come with your test kit. Make sure that whomever does the testing knows how to respond to a specific reading (test result).
Types of Chlorine
- Free Available Chlorine (FAC): Chlorine that has not yet reacted with any organic material.
- Combined Available Chlorine (CAC): Chlorine that has already reacted with organic material present in a hot tub or pool; therefore, it is much less effective.
- Total Available Chlorine (TAC): Is the sum of free available chlorine plus the combined available chlorine as per the formula TAC=FAC+CAC.
It is important to maintain the proper level of disinfectant.
Ultraviolet (U.V.) or ozone treatment systems help control bacteria, but they are not a substitute for disinfection. Ozone helps disinfection since it will destroy some of the material that uses up disinfectants. Special care should be taken with ozone because it can cause eye and lung damage. Make sure no ozone bubbles are entering the bathing area and there is no ozone smell. If you are using another form of disinfection such as ozone, it must be used in combination with chlorine or bromine to create a disinfection residual.
Measure pH and Water Quality
It is very important to maintain the pH of the water in the 7.2 to 7.8 range. Pool water out of this range reduces the disinfecting power of chlorine. It can also cause eye and mucous membrane irritation. Measure pH daily and maintain it in this range. Your pool supplier will carry test kits for pH, as well as chemicals to adjust the pH.
Chlorine is measured in parts per million (ppm).Stabilizer chlorine should be avoided unless you have an outdoor pool, and should not exceed 30-50ppm. The table below lists recommended ranges for both pool (less than 30°C/86°F) and hot tub (more than 30°C/86°F) water quality measures.
|Free Chlorine (less than 30ºC/86ºF)||0.5ppm||2.0-5.0ppm||5.0ppm|
|Free Chlorine (more than 30ºC/86ºF)||1.5ppm||3.0-5.0ppm||5.0ppm|
|Bromine (less than 30ºC/86ºF)||1.5ppm||3.0-5.0ppm||5.0ppm|
|Bromine (more than 30ºC/86ºF)||2.5ppm||5.0-8.0ppm||8.0ppm|
Total Alkalinity CaCO3
|Cyanuric Acid (outdoor pools only)||30ppm||30-50ppm||80ppm|
Your dealer can help you with more advanced chemical analyses.
Remember to use and store your pool chemicals safely as they can be dangerous. Follow safety instructions on the product label and safety data sheets.
Regular shock treatment is recommended
When combined, residual chlorine begins to accumulate in the water and can lead to unwanted odors and eye irritation. Shock treatment is a process for getting rid of the combined residual chlorine in a hot tub or pool. Ideally, shock treatment is done before the combined residual chlorine is more than 0.5ppm.
In hot tubs, you can also just replace all of the water instead of doing a shock treatment. The use of non-chlorine shock treatment can impact test kits by affecting accuracy when reading the total chlorine.
Most pool suppliers can provide instructions or chemicals for shock treating a hot tub or pool. This helps clear the water and remove contaminants. Make sure the chlorine level is back to normal before you enter the tub.
Keep the pump going 24 hours a day
Between periods of use, water in hot tub and pool’s plumbing lines can become stagnant and grow bacteria or fungus. You can prevent this by:
- Running a pump 24 hours a day to circulate water through all the pipes; or
- Setting a timer to turn the pump on for a few hours, at least twice a day, to flush out all the lines; and
- Making sure that all filters and pumps are maintained according to the manufacturer’s recommendations.
Some hot tubs have secondary circulation pumps that run 24 hours a day. These systems may bypass some water lines and still leave water sitting stagnant in those lines. Always ask your dealer or pool supplier for advice and recommendations
Clean your hot tub and pool regularly
Your cleaning schedule will vary depending upon how many people use your pool or hot tub and how much. As a minimum, it should be cleaned and restarted monthly, or as per the manufacturer’s instructions. You should also drain and clean your hot tub or pool if any of the following problems occur:
- Complaints of eye, ear or skin irritations after using the pool or hot tub; or,
- Proper disinfectant levels have not been maintained.
For more information on maintaining safe water quality in hot tubs and pools, contact your local environmental health office or your local pool and hot tub service provider.
For health and safety tips see HealthLinkBC File #27a Residential Hot Tubs and Pools: Health and Safety Tips.
For more HealthLinkBC File topics, visit www.HealthLinkBC.ca/healthfiles/ or your local public health unit.
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