Is It Safe To Swim in a Pool With Low Levels?

There’s nothing like a nice, refreshing swim in your pool during the summer, but the smell of chlorine in the pool water can be a bit annoying. Some people might consider lowering chlorine levels in the pool, but would swimming be safe if these levels are lower than required?

It is not safe to swim in a pool with low levels in the long term. An occasional swim is not likely to harm you seriously, but it’s risky nonetheless. Low chlorine levels create opportunities for dangerous microbes to thrive, increasing the chances of infections and other serious health problems. 

If you’re still unsure if you should go in or not, stick around! I’ll explain what low levels mean, why we chlorinate pools in the first place, and how to tell that a pool is not safe to swim or dive in.

In ground swimming pool with new vinyl liner being refilled with water ready for use

Why Pools With Low Levels Are Not Safe

Although it’s standard practice, the use of chlorine in pool water can make some people uncomfortable or wary. 

Knowing that chlorine is a powerful chemical gives the impression that it’s unsafe for humans to swim in, and the smell certainly doesn’t help. Consequently, some may believe lowering the pool’s chlorine levels is safer. However, doing so creates a dangerous environment to swim or dive in.

Countless living microorganisms can harm humans in different ways, from skin rashes to brain infections. A lot of these microbes can survive and thrive in the water. Chlorine, at the right amount, can kill most of them, allowing you to swim safely in your pool. In addition to sanitizing, chlorine prevents algae from growing and keeps the water clear.

If there isn’t enough chlorine in the pool water, many harmful bacteria can survive, along with algae and many other microbes. Because the water in your pool is stagnant and not flowing, unlike a lake or a river, these microorganisms can quickly multiply and make your pool water toxic. 

What Happens if I Swim in a Pool With Low Levels?

Generally speaking, there’s a low probability of you getting seriously sick from swimming occasionally in your pool with low levels, but it’s not zero. 

You may be fine and won’t risk your life, but the possibility of harmful microbes existing in the first place should give you pause. 

Suppose you have open wounds, even a tiny cut on your skin — the chances of getting sick or infected increase dramatically. 

Broken skin offers a point of entrance for microbes that would otherwise have a tough time entering your body. In this case, avoiding a pool with low levels is better altogether.

So, do not frequent a pool with low chlorine levels often or over a long time. The more often you swim in such an environment, the higher your chances of getting sick. 

Additionally, suppose you don’t add the correct chlorine amount in your pool for an extended period. In that case, you allow the surviving bacteria to grow and multiply, creating a petri dish in your pool.

What Should the Pool Levels Be?

A pool with low levels is unsafe, but that doesn’t mean you should fill the water with chlorine. As helpful as it is, chlorine is still a potent chemical that kills living microorganisms and can harm humans. 

Excess chlorine in your pool can cause dermatitis, eye irritation, and even respiratory illnesses.

Some standards determine the amount of chlorine you should use in a pool. It should be enough to kill dangerous germs but not enough to cause harm to the people swimming. 

The measurement unit used to determine the amount of chlorine needed in the water is ppm or part per million. One ppm means there is one part chlorine per 1 million parts water.

According to the CDC, chlorine levels in a pool should be between 1ppm and 3ppm. It’s important to remember that the chlorine levels decrease with time, and, as a result, so does the protection against germs and algae. 

To ensure the pool water is safe, you must test regularly and add chlorine to your pool at least once a week. Here’s a video that shows you how to test your pool water: 

How To Tell if a Pool Is Unsafe To Swim In

You don’t always have an immediate way of knowing if your pool is safe or not, but sometimes just using your senses can be helpful. Here are some signs of unsafe pool water that you can look for:

  • Murky water. If the pool water has poor visibility, there’s a high chance of chemical imbalance and water filtration and circulation issues. Make sure you solve these problems before swimming.
  • Green or Yellow Water. The water in your pool should be totally clear.  If your pool water is green or yellow, f, there’s likely algae or other impurities like metals in it. If that’s the case, your pool levels are too low.
  • Foam. A layer of foam on the water is not a good sign. Foam only appears when contaminants are in the water, and the pool levels aren’t adequate. 
  • Odors. There shouldn’t be any particular smell coming off the pool except for a faint hint of chlorine. If the water smells off or has a strong chlorine odor, the pool is contaminated and off balance. 

You can always ensure that something is wrong or right with the pool water by doing a water test. Use a test kit or a strip to continuously check the pool’s chemical levels to ensure it’s safe to swim in. If the results show that the levels are out of balance, even though the water looks okay, it’s not safe to go in.

If you’re not sure about a pool’s safety, an inspection is the safest way to go. Pools can fail safety inspections for a variety of reasons, which I’ve covered in my complete guide on the topic. Learn more by clicking the link.

pool cleaning and maintenance products


While they may seem like a “chemical-free” environment, pools with low chlorine levels are unsafe, primarily if used frequently and for a long time. Chlorine kills bacteria, algae, and other microorganisms, and leaving these organisms in your pool can be extremely dangerous to humans. 

As a result, insufficient chlorine could make the pool water a suitable environment for these microbes to thrive. To keep your pool water safe, ensure the chlorine levels are just right and check continuously.