What Should I Do If My Hot Tub Smells Bad?

A bad smell may indicate poor water sanitation or bacteria buildup. Shock the water, clean the filter, and ensure your sanitizer levels are correct.

Common Causes of Bad Hot Tub Odors

Several factors can cause a hot tub to develop an unpleasant smell. Identifying the source of the odor is the first step in fixing it.

1. Bacteria and Biofilm Buildup

Bacteria thrive in warm, damp environments, making your hot tub an ideal breeding ground. If your sanitizer levels are too low, bacteria and biofilm can develop, leading to a foul odor.

2. Dirty or Clogged Filters

Hot tub filters trap debris and contaminants, but if they aren’t cleaned regularly, they can become clogged and start to smell.

3. Poor Water Chemistry

Imbalanced water chemistry can create bad smells. Issues like high pH, low chlorine or bromine levels, and excessive organic waste can all lead to odors.

4. Old or Stagnant Water

If you haven’t drained and refilled your hot tub in a while, old water can start to smell due to a buildup of contaminants.

5. Mildew on the Hot Tub Cover

A damp, poorly ventilated cover can develop mold and mildew, which leads to musty smells that transfer to the water.

How to Get Rid of Bad Smells in Your Hot Tub

If your hot tub smells bad, follow these steps to fix the issue and prevent it from coming back.

1. Test and Adjust Water Chemistry

• Use a test strip or kit to check pH, alkalinity, and sanitizer levels.
  
  

• Adjust chemicals as needed to maintain proper balance:
  

• pH: 7.2 – 7.8
  

• Alkalinity: 80 – 120 ppm
  

• Chlorine/Bromine: 3 – 5 ppm
  

• If sanitizer levels are low, shock the water with a non-chlorine or chlorine shock treatment.
  

2. Clean or Replace the Filters

• Remove the filters and rinse them with a hose.
  

• Soak them in a hot tub filter cleaner solution for deep cleaning.
  

• If the filters are more than a year old or excessively dirty, replace them.
  

3. Drain and Refill the Hot Tub

• If your hot tub hasn’t been drained in over three months, a full water change may be necessary.
  

• Use a hot tub flush product before draining to break down biofilm and remove bacteria hiding in the pipes.
  

• Once drained, wipe down the interior with a spa-safe cleaner before refilling with fresh water.
  

4. Clean the Hot Tub Cover

• Remove the cover and inspect it for mold and mildew.
  

• Wipe it down with a mixture of white vinegar and water or a spa cover cleaner.
  

• Let the cover dry completely before placing it back on the hot tub.
  

5. Keep the Water Circulating

• Run the jets and circulation system daily to keep water moving and prevent stagnation.
  

• Increase filter cycle settings if the water starts to smell stale.
  

6. Address Persistent Odors with Enzyme Treatments

• If the smell persists, use an enzyme-based water cleaner to break down organic waste and prevent buildup.
  

• Follow the product instructions for proper dosage.
  

How to Prevent Hot Tub Odors

Once your hot tub smells fresh again, take these steps to keep it that way.

1. Maintain Proper Water Chemistry

• Test the water at least twice a week and adjust as needed.
  

• Keep sanitizer levels within the recommended range.
  

• Use oxidizing shock treatments weekly to prevent organic buildup.
  

2. Clean and Replace Filters Regularly

• Rinse filters weekly and do a deep cleaning once a month.
  

• Replace filters every 12 months or as needed.
  

3. Drain and Refill on Schedule

• Fully drain and refill your hot tub every 3-4 months.
  

• Use a plumbing flush to remove hidden bacteria before refilling.
  

4. Keep the Hot Tub Cover Dry and Clean

• Wipe down the cover once a month to prevent mold.
  

• Allow it to dry completely after use to prevent mildew growth.
  

5. Shower Before Entering the Hot Tub

• Rinse off lotions, deodorant, and body oils before getting in.
  

• Avoid using the hot tub right after applying perfumes or hair products.
  

6. Increase Circulation Time

• If you use your hot tub frequently, set the circulation cycle to run longer each day.
  

• More circulation helps prevent stagnant water and bacterial growth.
  

When to Call a Professional

If you've tried all these steps and your hot tub still smells bad, you may have a more serious issue. Consider calling a professional if:

• The odor is extremely strong or has a sewage-like smell.
  

• The water remains cloudy or foamy even after multiple treatments.
  

• There is visible mold or algae growth that won’t go away.
  

• Your hot tub’s plumbing system has persistent biofilm buildup.
  

A professional spa technician can help diagnose deeper issues and recommend solutions that keep your hot tub in top condition.

Enjoy a Fresh, Odor-Free Hot Tub

No one wants to soak in a smelly hot tub. By keeping up with regular maintenance, balancing water chemistry, and cleaning components properly, you can prevent bad odors from ruining your spa time. Stick to a consistent routine, and your hot tub will stay fresh, clean, and ready to enjoy whenever you need a relaxing soak.