Why Does My Spa Water Smell Bad?

Many people love to soak in their hot tub at the end of a long hard day. But the reality is that hot tubs do require ongoing maintenance to keep them functioning properly. Have you ever asked yourself: “why does my spa water smell bad?”

Here’s what’s happening and how to fix it:

Smelly hot tub water can indicate low levels of chlorine or bromine sanitizer, a dirty filter, or water with high levels of total dissolved solids likely from going too long in between water changes.

Luckily, all of those problems have simple remedies. And the solutions can easily be put into practice and just become part of your routine, taking just a few minutes per week.

If this is something you are facing, this article is just for you.

So we’ll cover all the possible causes, how to know which one applies to you, and how to fix each one, quickly and easily. Let’s get into it!

Does bad-smelling hot tub water mean anything?

Cloudy or smelly water in a hot tub can indicate a low pH, high alkalinity, or low chlorine levels. The issue is potentially harmful or at least unpleasant and should be addressed before getting in.

So, when you lift that lid on your hot tub and get a bad smell, you know you have a problem. This is often accompanied by cloudiness in the water. DO NOT GO IN!

The first thing to do is check pH and alkalinity.

If the pH is too low, you may notice a sharp, pungent smell. If you get a musty, stale odor, that is an indication that the pH is too high. High alkalinity can also be the cause of cloudy water.

Start by testing the Total Alkalinity (TA), which should be between 80 and 120 parts per million (ppm).

Then test the pH, which should be between 7.2 and 7.8 ppm. You should always adjust the TA first because if this is outside those parameters, you will have difficulty balancing the pH.

The bad smell may also be caused by poor sanitation, allowing a build-up of biofilm and bacteria in the water. Adding chlorine or bromine to the water regularly will solve this.

If you get a strong smell of chlorine when you lift the lid, don’t make the mistake of thinking this is a good thing either.

It is most likely caused by chloramines, which develop when the chlorine in the water mixes and reacts with the things you as a bather bring in with you – the oils, deodorants, perfume, and sweat, to name a few.

Shocking the water will eliminate this by increasing the chlorine level, which releases the free chlorine in the chloramines.

If you want to know more about keeping your hot tub clear of smells, see this recent article. I get more into biofilm; what it is, how it could hurt you, and how to get rid of it.

Just click that link to read it on my site.

How do I keep my spa water clean?

Keeping your spa water clean is simple enough – you just have to put together a maintenance program and stick to it. This should comprise:

  • Remove and rinse your filter at least every 3 weeks. This is just a matter of hosing it down and getting into the folds. I recommend the Filter Flosser on Amazon, which connects to your garden hose and allows you to easily get in the cracks of all the paper pleats in your filter.
  • Check the pH and alkalinity levels weekly to make sure the balance is right.
  • Change the water and thoroughly clean your hot tub every 3 to 4 months. 
  • Give your filter a deep clean every 3 months by soaking it in a 5-gallon bucket of cold water with a good quality cleaning agent overnight. Alternately with hot water, the soak time can be just 1 hour.
  • Add sanitizer multiple times per week as needed.
  • Shock the water once a week.

For the filter deep clean, there are lots of products on Amazon, but one I would recommend is Power Soak.

I add about half a cup to a 5-gallon bucket of hot water. Then I simply soak my filters in that for 1 hour. Rinse, and put back in, and I’m good to go.

I do that every 3 months.

Chlorine or bromine can be used as a sanitizer. The choice depends on personal taste, and I explained the differences in this recent article. But one is clearly better for hot tubs than the other.

Just click that link to read it on my site.

How do I know if my hot tub has bacteria?

The biggest indicator that a hot tub has high levels of bacteria is when sanitizer and shock have to be added much more frequently than they had been to maintain the same levels when tested. Unfortunately, bacteria won’t be seen in the water.

Over time, the water becomes contaminated with dead skin, sweat, oils from body lotions, deodorants, and perfume. 

This residue forms a biofilm on the surface of your hot tub, most of which gets caught in the filter, but some will find their way into the pump and pipework.

Chlorine – or bromine, if you prefer that – will kill off bacteria and keep your water clean and safe to bathe in.

But sometimes, things can go wrong, and you or one of your friends or family may develop some form of a rash following a hot tub session.

More often than not, a rash is caused by a chemical imbalance in the water, which is easy to resolve, and apart from a little discomfort, isn’t serious.

However, occasionally, a more serious problem can occur.

Hot tub folliculitis is not a common ailment for hot tub users, but it can happen. It is an infection of the hair follicles caused by a bacteria known as pseudomonas, and it can easily spread across the body as we have these all over.

Check out this recent article to find out how to get folliculitis out of your hot tub.

There is no cure, but the symptoms can be treated until it clears up naturally after a few days. The bacteria that causes it is easily destroyed just by following a few simple steps.

Just click on the link to read it here on my site.

How do I stop my hot tub water from smelling?

A smelly hot tub is likely caused by low pH, high alkalinity, low sanitizer, or water that has gone too long since the previous water change and now has high levels of total dissolved solids and/or biofilm.

If the smell is caused by an imbalance in the pH and alkaline levels, you need to address it. 

High pH signifies low acidity, so to lower alkalinity and pH, you should add an acid such as sodium bisulfate or even vinegar (acetic acid).

If alkalinity is fine, you just need to focus on the pH and ensure that it is the correct level on your test strip.

If the smell is due to chloramines, then shocking the water will clear this up. Sodium Dichlor is best for this as it is chlorine-based, and it is the free chlorine you want to release. But any chlorine-based hot tub shock should do the trick.

Smells can result from bromine reacting with the biofilm as well – sometimes described as a chemical or caustic odor – creating bromamines, and this can be treated similarly, but you should use a non-chlorine shock.

It is best to leave the hot tub with the jets running and the lid off for 30 minutes or more after adding chemicals to get rid of any gasses that are likely to develop.

As always, prevention is better than the cure, so to avoid bad smells, stick to your maintenance regime, including changing the water regularly.

For more information on how and when to change your hot tub water, check out this recent article.

Changing your hot tub’s water isn’t hard and you can easily just use a garden hose you already have on hand. However, that will take about 2 hours to drain, whereas I drain mine in 15 minutes!

Just click the link to read more on my site.

How can I make my hot tub water smell better? 

A well-balanced hot tub should have a neutral smell with just a faint aroma of chlorine. However, there are aromatherapy products that can scent the water without the damaging effects of bath bombs or oil-based products.

One thing everyone who owns a hot tub should understand, a hot tub is not a bath, and you cannot treat it in the same way.

Adding products such as Epsom salts and bubble bath may work in an ordinary bathtub, but if you put them in a spa, you are asking for trouble.

Epsom salts are particularly bad because of the high salt content, which can be extremely corrosive for your hot tub. Bubble bath should also be avoided because this will clog the filter and block the jets.

The only products that should be used in a hot tub are those made specifically for that purpose.

Check out this recent article on my website on the topic of using bath salts by clicking on the link.

If you want to improve your hot tub experience and add some aromatherapy, why not try some spa crystals like those in from Spazazz on Amazon  – just click on the link to see the latest prices.

The original Lavender Palmarosa aroma, Grapefruit Orange, Green Tea Peony, Pomegranate, Coconut Vanilla, and White Musk Jasmine Vanilla are all available.

The oil-free crystals do not affect the pH balance of hot tubs and do not leave any residues or clog filters.

Did I cover everything you wanted to know about why spa water can smell bad?

Lots of things can make your hot tub water smell bad.

Luckily, there are things you can do to improve the situation when it arises, but the main thing is to avoid it in the first place.

Maintaining your hot tub water and keeping it crystal clear is the best way to deal with bad smells.

I hope this gives you the information you need to keep your hot tub in tip-top condition, so you don’t have the disappointment of having to miss out on a good soak. If you need any more advice, just reach out to me – I’d be glad to help.

And don’t forget to click on those links to read other associated articles here on my site.


Photo which requires attribution:

Yellowstone NP trip by ilya_ktsn is licensed under CC2.0 and was cropped, edited, color-adjusted, and had a text and graphic overlay added

Jeff Campbell

Jeff Campbell is a husband, father, martial artist, budget-master, Disney-addict, musician, hot tub lover, and recovering foodie having spent over 2 decades as a leader for Whole Foods Market.

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