Why Does My Hot Tub Smell Like Ammonia?

Few things can disrupt your plan of a warm relaxing evening in your hot tub. One of them is when the hot tub smells like ammonia. So why does the hot tub smell like ammonia? Here is the answer to that.

A hot tub will smell like ammonia when there are body oils, sweat, and urine in the hot tub water. These contaminants react with the chlorine in the water to produce combined chlorine or chloramines which will cause the hot tub to smell like ammonia.

But there is more to know and this post digs right into the topic. When you are done reading this article, you will know the reasons your hot tub smells like ammonia as well as how to get rid of the smell.

Let’s dive in.

Is It Normal For Hot Tub Water To Smell Like Ammonia?

It’s not normal for hot tub water to smell like ammonia. When a hot tub starts to smell like ammonia, it is because there are too many contaminants in the water that are causing the sanitizer to be ineffective. Since the sanitizer has been rendered ineffective, the contaminants in the water will accumulate freely and cause an ammonia smell in the hot tub.

When your hot tub starts to produce an ammonia smell, it’s because the hot tub water has not been well sanitized or there is not enough sanitizer in the water. An ammonia smell in the hot tub also means that the hot tub is not being properly maintained.

Hot tubs need a regular dose of sanitizing chemicals weekly and if you use chlorine, you need to shock the hot tub once a week to destroy any contaminant in the water. When the hot tub doesn’t get its needed dose of sanitizing chemicals, the hot tub becomes defenseless and contaminants will accumulate easily in the water.

The contaminants that cause ammonia smell in a hot tub include sweat, urine, body oils, and the likes. These contaminants are waste products that are passed out from the body. When these wastes get into the hot tub water, they clash with the sanitizing chemical.

The chemicals are meant to destroy these contaminants but if there isn’t enough chemical in the water, then the contaminants wouldn’t be destroyed. Instead, they would bind with the little sanitizer in the water to produce chloramines which then leads to the offensive ammonia smell that you perceive.

So if you think of it, the hot tub shouldn’t smell like ammonia if the water is well treated. Your hot tub shouldn’t even smell at all.

Related Read: What causes Chlorine Smell in a Hot Tub?

What Causes Ammonia Smell In My Hot Tub?

The ammonia smell in a hot tub is caused by the presence of chloramines in the water. Chloramines are produced when chlorine sanitizer combines with ammonia. The combination produces the offensive ammonia smell in the hot tub.

Ammonia smell in a hot tub is caused by the presence of used up chlorine that has combined with ammonia. When you add chlorine to a hot tub, the chlorine battles and destroys the contaminants in the water. But as the chlorine destroys contaminants, there would be less chlorine in the water. The more contaminants in the water, the lower the level of active chlorine.

When the active chlorine level gets lower than 1 ppm, it becomes ineffective at destroying contaminants. This means the hot tub becomes defenseless and the contaminants like sweat and urine can accumulate freely in the water.

These contaminants (sweat and urine) are formed from perspiration. This means ordinarily, these contaminants are waste products (which means they would smell bad). When they now bind with the used up chlorine in the water, the result of the combination is an offensive smell of ammonia in the hot tub.

So can you use the hot tub if it smells like ammonia? Let’s take a closer look.

Can I Use My Hot Tub If It Smells Like Ammonia?

You shouldn’t use a hot tub if it smells like ammonia because the hot tub water at that time is unsafe and unhealthy for soaking. Also, running your hot tub when it smells like ammonia is unsafe for the hot tub components.

When the hot tub smells like ammonia, it means the water is not properly treated and has been contaminated. Soaking in hot tub water that has been contaminated can result in serious health problems.

You wouldn’t even get the satisfaction and relaxation you were hoping for if the hot tub smells like ammonia. You wouldn’t be able to sit in the water when it smells foul. The smell of ammonia in large quantities is also not good for your lungs and eyes.

Using a hot tub that smells like ammonia is very risky. Even if you don’t pick up any health issues by using the water, you will come out of the hot tub smelling like ammonia too.

The ammonia smell in the water is also an indication that the total alkalinity of the water is off.  When the total alkalinity of your hot tub is off, it would be tough to keep the pH levels in check. The wrong pH levels will affect the water chemistry and that can lead to other problems not just for you but for the hot tub.

Hot tub scale formation, staining, discoloration, clogged pipes, clogged filters, and jets are just some of the problems that will affect your hot tub components when you run the hot tub while the water smells like ammonia.

Now that you know you can’t use your hot tub when it smells like ammonia, how can you get rid of the ammonia smell in your hot tub? Let’s find out below.

Related Read: How To Raise Alkalinity in a Hot Tub?

How To Get Rid Of The Ammonia Smell In Your Hot Tub

The best way to get rid of the ammonia smell in a hot tub is to shock the hot tub using chlorine shock. When you shock the hot tub, the shock will break the bond between the used chlorine and ammonia. The bond break will release more free or active chlorine to destroy the ammonia causing the smell.

But there are a few things to do before you can shock the hot tub.

Uncover The Hot Tub

The first thing to do is to uncover the hot tub. While shocking the hot tub to get rid of the ammonia smell, you need to ensure the hot tub cover is not on.

Turn On The Jets

The next step is to turn on the jets. Depending on how much water is in the hot tub, you can either turn the jets on high setting or low setting.

If the ammonia smell is strong or you have a large hot tub, you should turn on the jets on a high setting. When the jets are on, there is increased water circulation in the hot tub. This ensures that when you add the chlorine shock, it is well absorbed by the water.

Measure The Chlorine Shock

The next step is to measure the amount of chlorine shock needed. There are usually instructions indicated on the container of the chlorine shock. Ensure to only add the right amount of chlorine shock to the water as indicated on the container.

To get rid of the ammonia smell, you need the chlorine level to be as high as 10 ppm (parts per million) in the water.

Ordinarily, the chlorine levels in your hot tub shouldn’t exceed 5ppm but since you are trying to destroy the ammonia in the water while also raising the chlorine levels, you need to super-chlorinate the hot tub. This means you need a very high dose of chlorine shock in the water and 10 ppm usually works.

Shock The Water

When you have measured the right amount of hot tub chlorine shock, you should then add it to the water while the jets are still on. You can add the shock directly into the hot tub or mix it with water first. Either way, just ensure you add the correct amount.

Keep The Jets Running

After adding chlorine shock to the water, keep the jets running. You should also keep the hot tub uncovered for up to 20 minutes. This gives the shock enough time to oxidize the water and destroy the ammonia.

Test The Water

After a few hours, you should use a hot tub test strip to test the water in the hot tub. You should first test for the chlorine levels of the water to be sure it has been raised.

Test for both the total chlorine and free chlorine. If the Shock worked as well as it should, the level of free or active chlorine in the water would be the same as the total chlorine level. If this is the case, then that means you have successfully destroyed the chloramines or combined chlorine in the water.

But if you test for the chlorine levels and the combined chlorine is still more than 0.5 ppm, that means there is still ammonia in the water. In this case, you need to shock the water again but you should consult the manufacturer’s instructions to know how long you have to wait before you shock the water again.

You should also test for the chemical properties of the water. The pH level, total alkalinity, and calcium hardness might have been affected by the presence of chloramines or by the shock you added. You should adjust these chemicals as needed to ensure the hot tub is safe for use again.

Last Resort

If you have shocked the hot tub and for some reason, the water doesn’t get clear or you can still smell the ammonia, you need to drain the hot tub. Chances are you haven’t drained the hot tub in a while and that’s why it’s difficult to get rid of the contaminants.

So drain the hot tub, clean it and refill it. Then add the right amount of chemicals to sanitize the water for use.

Related Read: How To Keep Hot Tub Water Clear?

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How To Prevent Ammonia Smell In Your Hot Tub

Getting rid of the ammonia smell in your hot tub is one thing but preventing it is another.

To prevent your hot tub from smelling like ammonia, you need to sanitize the water regularly and maintain the hot tub properly. This means you should:

  • Add the right amount of chemicals as at when due.
  • Shock the hot tub once a week if you use chlorine as the hot tub sanitizer.
  • Clean and wash the filters every month. If the filters get damaged, you should replace them.
  • The jets and plumbing lines of the hot tub should also be cleaned monthly. You should add a line flush to the plumbing lines of the hot tub to flush out any biofilm that can cause chloramines in the water.
  • Always shower before you get into the hot tub to prevent you from introducing contaminants like swear and urine into the water.
  • Use hot tub fragrances or spa crystals. These products give the hot tub a very nice smell. You shouldn’t use these products to cover a bad smell in the hot tub. A bad smell is an indication that something is not right with the hot tub.
  • You can also use scented candles and flowers around the hot tub but ensure to keep them out of the water always.

No More Smell

Overall, hot tubs smell like ammonia when the hot tub water isn’t properly treated with the needed chemicals.

The lack of chemicals allows contaminants to roam free in the water and this causes the offensive smell of ammonia. If you notice your hot tub is starting to give off an offensive smell, you should shock the water immediately to get rid of the smell.

But remember, your hot tub wouldn’t smell if you maintain it properly. Good hot tub maintenance keeps the smell away.


My name is Alex and I live in the Northeast of England. I want to combine my love of swimming with my growing knowledge of all things Spa. This site will focus on Swimming, Pools, Home Spas, Saunas, Hot Tubs and any way you can think of to relax and unwind

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