Ever sat in your hot tub and thought, "Hmm... this water smells a bit like old socks"? Don’t worry, you’re not alone. Short answer: you should change your hot tub water every 3–4 months. Maybe more often if your tub's the life of the party.
Whether you’re soaking in an Acrylic Hot Tub, enjoying the simplicity of a Rotomoulded Hot Tub, or going rustic with a Wooden Hot Tub, clean water matters. Let’s dive into the why, when, and how of hot tub water changes.
Sure, you’ve got chemicals and filters doing their thing. But they can only go so far. Eventually, even the cleanest-looking water turns into a cocktail of stuff you'd rather not swim in.
TDS is everything your water collects: sweat, dead skin, oils, shampoo residue, and leftover chemicals. Over time, it builds up and stops your water from responding properly to treatments.
Think of it like brewing tea over and over with the same bag, eventually, it just doesn’t work anymore.
As TDS increases, your sanitiser gets bogged down. It has to fight through all the gunk before it can zap bacteria. At a certain point, it just can’t keep up.
That’s when your water starts looking off, feeling weird, and smelling worse than your gym socks.
Your filter is working hard, bless it. But it can’t catch everything. Lotions, body oils, and tiny particles sneak past it.
Changing the water is the only way to get a full reset.
Clear, clean water isn’t just for looks. It’s about comfort, hygiene, and peace of mind. No one wants to sit in a cloudy mystery brew.
If the water feels off, it probably is. Time to drain.
Let’s cut to the chase. How often should you change hot tub water in the UK?
Across the board, experts agree: change your hot tub water every 3 to 4 months. That’s enough to keep things fresh without being a hassle.
Even top-rated hotels do it about every three months. If they can, you can too.
Want a formula? Try this:
(Hot tub volume in litres ÷ 10) ÷ number of daily bathers = days between water changes
For example, 1200L ÷ 10 = 120. Divide that by 2 users = change your water every 60 days.
Not all hot tubs or owners are built the same. Here’s what can fast-track your next drain day.
More people = more stuff in the water. Simple math. A solo soak once a week? You can stretch your schedule.
But if your tub's your social hub, you’ll need to change the water more often.
Skipping a quick rinse? That means more body oils, cosmetics, and dirt hitting the water.
The cleaner you are before the dip, the longer your water lasts.
Chlorine, bromine, salt, or minerals, each has different strengths. Some systems need more frequent top-ups and water changes than others.
It’s all about how much work your chemicals have to do.
If you’re lazy with water testing or forget to clean the filter, guess what? Your water won't stay clean for long.
Consistent maintenance buys you more soak time.
Bigger tubs have more water to dilute contaminants. Smaller tubs get overloaded faster.
So, yes, size does matter here.
Live in a hard water area? You’ll likely see scale build-up sooner. It messes with your heater and your balance.
Hard water = harder work.
Still wondering how often should I change the water in my hot tub? Let your tub do the talking.
No matter how many chemicals you throw in, the water stays cloudy or bubbly? It’s time.
Cloudy water is a dead giveaway.
If your pH and alkalinity are all over the place, your water is probably overloaded.
Constant adjustment = time to change.
A whiff of damp dog or sour towel? Not normal. That’s bacteria setting up camp.
Don’t ignore your nose.
White crust or brown tinges around the shell or jets? That’s scale or mineral residue.
It’s not just ugly, it can clog your components too.
Got a TDS meter? Anything above 1500 ppm means it’s time to start over.
A full water change isn’t as scary as it sounds. It’s all about prep and timing.
Before you empty, run a pipe flush to break down the gunk inside your plumbing. Let it circulate before draining.
Think of it like flossing before brushing.
Use the built-in valve if you’ve got time. Want it fast? Use a submersible pump.
Just make sure the hose drains away from your patio.
Once drained, give the shell a proper wipe-down. Use a spa-safe cleaner and rinse thoroughly.
Don’t forget the jets and filter housing!
Use a hose filter while refilling to reduce limescale. Then test your water, balance the pH and alkalinity, and add sanitiser.
Don’t skip this step – it sets the tone for the next few months.
Now, can I change hot tub water once a year? In theory, yes. But in reality? Probably not a good idea.
If you’re a maintenance superstar – testing water, cleaning filters, adjusting levels – you can push the 4-month mark.
Maybe even 5.
Clarifiers bind up small particles for easier filtering. Enzymes break down oils and organic gunk.
They help, but they don’t replace fresh water.
No matter how clean you think your tub is, water ages. Bacteria and TDS don’t care how busy your week was.
Changing the water every 3–4 months keeps your hot tub healthy, safe, and fun.
Whether you’ve got a modern Acrylic Hot Tub, a lightweight Rotomoulded Hot Tub, or a charming Wooden Hot Tub, the answer stays the same.
How often should you change hot tub water UK? Stick to every 3 to 4 months, even in winter. If you’re using it more or skipping maintenance, that window gets shorter.
How often do hotels change hot tub water? Every 3 months. That’s a great benchmark.
So, set a reminder. Don’t wait for the smell. And enjoy every soak with confidence, knowing your water’s as fresh as it should be.
To explore more or upgrade your spa experience, check out our full Hot Tubs collection.
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