Is White Mold In Hot Tub Dangerous? Latest Tips 2023

When it comes to owning a hot tub, maintaining cleanliness and hygiene is of utmost importance. One common concern among hot tub owners is the presence of white mold.

In this article, we will explore whether white mold in a hot tub is dangerous and provide insights into how to address this issue effectively.

Do Not Forget to Read About: Best and Latest Air Purifiers

Understanding White Mold

White mold, also known as hot tub slime or biofilm, is a type of fungal growth that can develop in the moist and warm environment of a hot tub. 

It often appears as a slimy white or gray substance and can spread across surfaces such as the walls, filter cartridges, and plumbing system.

Fuzzy White Growth: The most apparent sign of white mold is the presence of a cotton-like or fluffy white growth on the surface of infected plants. This growth, also known as mycelium, is the visible part of the fungal infection and can spread rapidly across the plant.

Water-Soaked Lesions: White mold often starts as water-soaked lesions on plant tissues. These lesions are initially small, but they expand and become sunken as the disease progresses. They may appear on leaves, stems, flowers, or fruits.

Rotting and Wilting: As white mold progresses, infected plant parts may start to rot and become slimy. This rotting can cause wilting, leading to a general decline in the plant’s health.

Causes of White Mold in Hot Tubs

Now, we will explore the primary factors contributing to white mold growth, including high humidity and moisture levels, inadequate sanitization and maintenance, and the presence of organic matter.

High Humidity and Moisture Levels:

Hot tubs create a warm and moist environment, which is ideal for the growth of white mold. The combination of high water temperatures and enclosed spaces with limited airflow can lead to excessive humidity. Factors contributing to high humidity include:

a. Insufficient Ventilation: Inadequate air circulation in and around the hot tub can trap moisture, creating an environment conducive to mold growth.

b. Improper Cover Usage: Improper use or neglecting to use a hot tub cover when the tub is not in use can trap moisture and raise humidity levels.

c. Water Splash and Evaporation: Frequent splashing and evaporation of hot tub water can increase humidity levels in the immediate vicinity, promoting mold growth on surfaces.

Inadequate Sanitization and Maintenance:

Proper sanitization and maintenance are crucial for preventing white mold growth in hot tubs. Neglecting these aspects can lead to the proliferation of bacteria and fungi. Contributing factors include:

a. Inadequate Chlorine or Bromine Levels: Insufficient levels of sanitizing agents in the water can allow microorganisms, including white mold, to thrive.

b. Irregular Water Testing and Balancing: Failure to regularly test and balance the water’s pH and alkalinity levels can create an environment favoring mold growth.

c. Poor Filtration System: A malfunctioning or poorly maintained filtration system may not effectively remove contaminants from the water, providing a breeding ground for mold.

Presence of Organic Matter:

The presence of organic matter, such as body oils, sweat, dead skin cells, and debris, provides nutrients for white mold growth. Factors contributing to the accumulation of organic matter include:

a. Inadequate Cleaning Practices: Insufficient cleaning of the hot tub surfaces, including the walls, seats, and filter, can lead to the buildup of organic matter.

b. Contaminated Water Sources: Using untreated or unfiltered water in the hot tub can introduce organic matter and microorganisms, increasing the risk of mold growth.

c. Biofilm Formation: Biofilms are slimy layers that can develop on hot tub surfaces, providing a fertile environment for mold and other microorganisms to thrive.

Is White Mold In Hot Tub Dangerous

Potential Health Risks: Is White Mold In Hot Tub Dangerous

While the presence of white mold in a hot tub may be unsightly and unappealing, it is typically not considered dangerous to human health. However, it can contribute to various issues that may indirectly affect your well-being. Some of these include:

1. Skin Irritation and Allergies

Contact with white mold or its byproducts can lead to skin irritation and allergic reactions in certain individuals. Symptoms may include itching, redness, rashes, or hives. People with existing skin conditions or allergies may be more susceptible to these reactions.

2. Respiratory Problems

Inhaling mold spores, including those from white mold, can potentially trigger respiratory issues. Individuals with asthma, allergies, or sensitive respiratory systems may experience coughing, sneezing, wheezing, or shortness of breath.

However, it’s important to note that severe respiratory problems from white mold in a hot tub are rare.

3. Eye and Ear Infections

White mold can sometimes cause eye and ear infections if it comes into contact with these areas. Symptoms may include redness, itching, discharge, or discomfort. Prompt medical attention is advisable if you experience persistent or worsening symptoms.

How Do You Get Rid Of White Mold In A Hot Tub?

Now, we will provide a detailed guide on how to effectively get rid of white mold in a hot tub, ensuring a safe and enjoyable experience for your future soaks.

Step 1: Identification and Documentation

Begin by taking pictures of the white water mold in your hot tub. These photographs will serve as a reference for future identification and can help you track the progress of your treatment efforts.

Step 2: Decontamination with Chlorine

To eliminate white water mold, you need to decontaminate the spa by super-chlorinating the water. This can be achieved by using granular chlorine, granular bromine, or lithium. Maintain a chlorine level of 20ppm or higher for a duration of 72 hours for optimal results.

Step 3: Proper Chlorine Dosage

For effective treatment, add 2.5 ounces (5 tablespoons or 75 grams) of chlorine for every 100 gallons (400 liters) of spa water or an appropriate proportion based on your tub’s volume. If desired, you can add slightly more chlorine, as an extra dosage won’t cause harm.

Step 4: Ensure Full Circulation of Chlorinated Water

To distribute the chlorinated water throughout the entire plumbing system, adjust diverter valves to the midway position and ensure all jets, valves, waterfalls, and aerators are open. It’s also important to bleed some chlorinated water through the drain at the beginning of the process. This is crucial as built-in drains in the plumbing can be a dead-end where the chlorine may not reach naturally.

Step 5: Monitoring Chlorine Levels

Check the chlorine levels after 24, 48, and 72 hours. If the test strips indicate chlorine levels below the maximum, treat the hot tub with chlorine again. Repeat the chlorine readings at the specified intervals. During this decontamination process, avoid using the hot tub.

Step 6: Addressing Mold Flakes

Although the chlorination process kills white water mold, it does not eliminate flakes completely. Additional steps are required to ensure thorough removal. After 72 hours of successful chlorination, proceed with the following actions:

a. Remove and clean the filter to get rid of any accumulated debris and mold spores.

b. Clean the plumbing system using a suitable cleaner, such as Spa Marvel Cleanser, to eliminate any remaining mold particles.

c. Drain the hot tub completely to remove any stagnant water and potential mold reservoirs.

d. Install a clean filter and refill the hot tub.

Step 7: Flushing Out Remaining Mold Flakes

While refilling the hot tub, ensure all jets are turned on to facilitate the flushing out of any remaining mold flakes. Observe the water closely during this process. If you notice a significant number of flakes, it may be necessary to drain the hot tub again and refill it. However, if only a few flakes are present, your filter will collect them or they can be manually removed.

Step 8: Water Testing and Balancing

After completing the treatment and refilling the hot tub, it is crucial to test the water and ensure it is properly balanced. Regularly test and maintain the appropriate pH, alkalinity, and sanitizer levels to prevent future mold growth and maintain a clean and healthy hot tub environment.

Preventing and Addressing White Mold

To ensure a clean and safe hot tub experience, it’s crucial to take preventive measures and address the issue of white mold promptly. Here are some practical steps to follow:

1. Regular Cleaning and Maintenance

Maintain a consistent cleaning routine for your hot tub. This includes regular scrubbing of surfaces, cleaning the filter cartridges, and treating the water with appropriate sanitizers. Follow the manufacturer’s instructions for recommended cleaning products and procedures.

2. Proper Water Chemistry

Maintain balanced water chemistry by regularly testing and adjusting pH, alkalinity, and sanitizer levels. Imbalanced water can create an environment conducive to mold growth. Consult a professional or refer to your hot tub’s user manual for specific guidelines.

3. Adequate Ventilation

Ensure proper ventilation around your hot tub area. Good airflow can help minimize moisture buildup and discourage mold growth. Consider installing a ventilation system or keeping the hot tub in a well-ventilated location.

4. Drain and Refill

Periodically draining and refilling your hot tub can help remove any existing mold or biofilm. Follow the manufacturer’s recommendations regarding the frequency of water replacement.

5. Professional Inspection

If you notice persistent white mold growth or have concerns about the condition of your hot tub, it’s advisable to seek professional assistance. A qualified technician can inspect your hot tub, identify any underlying issues, and provide appropriate solutions.


In conclusion, while white mold in a hot tub may not pose a direct threat to your health, it can contribute to various issues that may affect your well-being.

Taking preventive measures, maintaining proper cleanliness, and promptly addressing the presence of white mold are essential for a safe and enjoyable hot tub experience.

Remember to consult professionals when necessary and prioritize regular maintenance to keep your hot tub in optimal condition.

Frequently Asked Questions (FAQs)

Can white mold in a hot tub make you sick?

White mold can potentially cause health issues, particularly for individuals with allergies or weakened immune systems. It is essential to address the mold growth promptly and take necessary precautions to prevent any adverse health effects.

How quickly does white mold grow in a hot tub?

The growth rate of white mold can vary depending on several factors, such as temperature, humidity, and the presence of organic matter. In optimal conditions, mold can start to develop within a few days to a couple of weeks.

Is white mold a sign of a poorly maintained hot tub?

White mold growth can be an indicator of a poorly maintained hot tub. Neglecting regular cleaning, sanitization, and maintenance can create an environment conducive to mold growth.

Can I use bleach to remove white mold from my hot tub?

Bleach can be effective in removing white mold from a hot tub. However, it is important to follow the manufacturer’s instructions and ensure proper ventilation during the cleaning process. Alternatively, there are mold-specific cleaners available that can effectively eliminate mold without the use of bleach.

Will white mold come back after cleaning the hot tub?

If the underlying causes of mold growth are not addressed, there is a possibility of white mold returning even after cleaning the hot tub. Proper maintenance, regular cleaning routines, and maintaining the appropriate water chemistry balance are crucial to prevent mold from reappearing.

Can I continue using my hot tub while treating white mold?

It is generally recommended to refrain from using the hot tub while treating white mold. This ensures the effectiveness of the cleaning and disinfection process, prevents further contamination, and reduces the risk of inhaling mold spores.


David Rouse (2003) – Eliminating Mold & Slime in Swimming Pools

Kristen Park - Specialised Content Writer for Caresh Fresh

My name is Kristen Park and I am a senior writer specialising in how-to guides and home cleaning information at Cares Fresh. As a researcher, I take pride in digging deep to find every small detail on a topic and explaining it in a way that is easy for the reader to understand.