How Often Should You Change Hot Tub Water?

We recommend changing your hot tub water every 3 to 4 months. That means draining and refilling it around 3–4 times a year. If your hot tub gets used a lot, especially by more than one person, closer to every 3 months is a safer bet.

Keeping the water clean isn’t just about looks. It helps your spa run properly, stay fresh, and feel more relaxing. Here’s what you need to know.

Why do you need to change the water?

Even when your water looks clear, it still builds up things like oils, dirt, and chemical residue over time. The longer you leave it, the harder it gets to balance the chemicals and keep it fresh.

Here are some good reasons to change your hot tub water regularly:

• Cleanliness: Water collects sweat, lotions, and skin cells even if you can’t see them.
• Jet and filter health: Fresh water helps your filters and jets last longer and work better.
• Smell: Old water can start to smell stale, even when treated with chemicals.

We go into more detail in our guide on how much chlorine to use if you’re struggling with water care.

How can I tell when it’s time to change the water?

You don’t always have to wait for the 3-month mark. Sometimes your spa will show signs that it needs fresh water sooner.

Look out for these signs:

• The water looks cloudy, murky, or foamy
• There’s a strong smell, even after adding sanitiser
• You keep adding chemicals but the balance still won’t hold

How to make your hot tub water last longer

If you want to get closer to the 4-month mark, a few simple habits can help. These will reduce how much dirt and bacteria get into the water.

• Shower before getting into the tub
• Use a well-fitting insulated cover when not in use
• Stick to the right amount of chlorine or bromine
• Rinse and clean your filter weekly (see our filter cleaning guide)

These steps can help keep your water clearer for longer — and reduce the number of chemical adjustments you need to make.

Related reading

Want to learn more about caring for or choosing the right hot tub? These guides will help:

• Compare hot tub models
• Are hot tubs worth owning?
• How much do hot tubs cost to run?
• Hot tub sizes and dimensions
• How much chlorine to add to a hot tub

If you’re ever unsure or need help with your water care, you can reach out to us anytime. We’re happy to guide you.