How Often Should You Change Hot Tub Water?

How Often Should You Change Hot Tub Water?

Change hot tub water? The mere thought might seem like a hassle. But don't be deceived by the calming bubbles and therapeutic warmth – letting water sit too long without a change can transform your serene spa experience into a bubbling cauldron of germs and grime. Regular water changes are imperative to maintain a healthy, hygienic hot tub experience. 

Frequency of Changing the Water 

If you're new to hot tub ownership or curious, you might wonder how often you should replace that water. While a general rule is every three months, some factors might cause you to adjust that timeline. 

Crunching the Numbers: Your Hot Tub's Volume & Bather Load 

Yes, there's a bit of math involved. Knowing your hot tub's capacity and estimating the average number of users can give you a tailored schedule for water changes.

Hot Tub Size Matters 

  • 2-seater spa: Approximately 170 gallons (or 650 liters) 
  • 4-seater hot tub: Around 330 gallons (or 1250 liters) 
  • Large spa for 7-8 people: Between 475 and 610 gallons (1800 to 2300 liters) 

Your owner's manual should provide the exact volume for your specific model. If it's misplaced, the manufacturer can assist. 

  • Bather Load: The average number of users and the frequency of usage affect how quickly the water quality can deteriorate. 
  • Water Change Formula
    • Hot tub volume ÷ 3 ÷ estimated average bather load 
    • For instance, a 170-gallon spa with an average of 2 bathers suggests changing the water every 28 days. In contrast, a 475-gallon spa would be every 79 days under the same conditions. 

Still, remember that these are guidelines. Factors like local water quality, hot tub location (indoor vs. outdoor), and maintenance habits will influence the exact timing. 

Signs You Need a Water Change 

  • Cloudy Water: If the clarity of your spa water starts resembling milk more than water, it's time for a change. While spa shocks can sometimes clear up minor murkiness, persistent cloudiness is a tell-tale sign. 
  • Foamy Spa: While a bubble bath sounds fun, foamy hot tub water isn't. Initial remedies like foam removers can be temporary fixes. For a long-term solution, a complete water change is best. 
  • Unpleasant Odors: A well-maintained hot tub shouldn't emit any strong odor. Changing the water is likely the only solution if a nasty stench lingers, even after adjusting the chemical balance. 

Why Changing the Water is Crucial 

Neglecting to refresh your hot tub water can lead to the following: 

  • Supersaturation: This causes scaling on the tub's fixtures, filter, and pump, leading to potential equipment damage and hefty repair costs. 
  • High Total Dissolved Solids (TDS): As body oils, sweat, cosmetics, and other contaminants accumulate, the water's ability to mix with sanitizers diminishes. This results in murky, possibly malodorous water, ruining the spa experience. 


Regular hot tub water changes are essential for a safe and enjoyable spa experience. Routine testing and vigilance for signs like cloudiness or foam will ensure your hot tub remains a haven of relaxation. After all, nothing beats the peace of mind that comes from knowing you're soaking in clean, fresh water.