Is Purple Pool Water Safe To Swim In?

Is purple pool water safe to swim in

Imagine waking up one hot weekend at the beginning of spring or the middle of summer to take a dip in your swimming pool only to find yourself staring at purple water. While the sight might be beautiful, it’s definitely not natural and can be caused by a variety of reasons.

After seeing it if you’re wondering whether it’s safe to swim in the purple pool water, it definitely is not. Unless the water takes a lavender hue due to poolside lighting, it’s definitely the result of poor chemical balance or harsh chemical reactions. Here’s everything you need to know about how purple pool water is bad for your health, how to treat the water, and the things you need to do to prevent it.

Key Takeaways

  • Your pool water can turn purple for a variety of reasons.
  • Purple or lavender pool water can look pretty but is a health hazard.
  • Treating purple pool water requires the expertise of a pool technician or years of pool maintenance yourself.

The Mystery of Purple Pool Water

The mystery of purple pool water
The mystery of purple pool water

Usually, water is transparent, but pool water has a blue tint to it due to the addition of chlorine to keep the water free from algae. This is the default color of pool water in normal circumstances. However, one of the most common pool problems many pool owners face is the pool water turning purple or lavender.

In most instances, homeowners think that the color change has occurred due to algae formation and furiously dump as much algaeecide in the pool only to find out that things have gotten worse. To make sure you don’t make this common mistake you need to learn the proper reasons why pool water can go purple.

Combination of copper and cyanuric acid
Combination of copper and cyanuric acid

Combination of Copper and Cyanuric Acid

Cyanuric acid is a common chemical component found in chlorine (the most common pool algaecide) and pool shock tablets or liquids. When this chemical combusts with a high level of copper presence in pool water, it causes the water to turn purple. Copper levels in pools can be usually maintained with other chemicals and the copper heat exchanger of your pool, but if galvanized corrosion occurs in the copper heat exchanger it leads to excessive copper discharge, creating the perfect situation for pool water turning purple.

Combination of Copper and Manganese

The second most common reason for pool water turning purple is the combustion of copper and manganese. Though it causes the pool water to go purple, it isn’t nearly as bad as cyanuric acid which leaves tough stains on the pool walls and sometimes the floor.

The resulting combustion of copper and manganese generally affects the surface level of the pool water, not the entire pool itself which is why it’s usually considered easier to clean than a combustion of copper and cyanuric acid.

High Copper Levels in the Local Water Source

Commercial copper heat exchangers are usually built with a certain filtering threshold in mind. But if the local water source for your swimming pool is high in copper content, then the copper exchanger won’t be able to function properly. This leads to an excess flow of copper in the pool which reacts with cyanuric acid.

Whether this is the case can only be determined through a test with a professional water testing kit. CPY readings of 30-50 ppm are the standard mineral level in regular pool water, but if the readings come to more than that then it will definitely react with cyanuric acid and cause the water to go purple.

Is Purple Pool Water Safe to Swim in?

Is purple pool water safe to swim in
Is purple pool water safe to swim in

Given the reason why pool water turns purple is due to chemical imbalances, it’s safe to say that purple pool water is definitely not safe to swim in. Swimming in purple pool water can pose a wide variety of health risks such as itchy skin, eye irritation, rashes, ear pain, and more.

Also taking a dip in the purple water can leave a purple tint on your skin and hair which can be difficult to wash off depending on how bad the contamination of pool water is. Purple pool water is only safe to swim in if it’s the result of poolside lighting giving the water a purple or lavender hue.

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How to Correct Purple Pool Water?

How to correct purple pool water
How to correct purple pool water

Though purple pool water can be a bothersome problem to have, fortunately, it’s easy enough to deal with for a professional pool technician. Don’t try to solve the problem by yourself, unless you’re accustomed to it. If you are, just follow these simple steps:

  • First, drain the pool water to at least half the pool level before slowly starting to refill it. As you refill, stop after filling every couple of feet and take CYA readings until they hit normal levels (30-50 ppm).
  • Once the pool has been refilled, apply generous amounts of metal remover depending on the size of your pool to separate the metals from the water and lighten the stains.
  • The sequestering process can take anywhere from a few hours to a couple of days. Once the process has been finished use the pool filter and a metal filtering product for pools to remove any final touches of stain from the pool floor or walls.
  • Clean the filter and apply 2-3 doses of mineral treatment to dissolve the final traces of stain left.

How to Prevent Purple Pool Water?

The best way to prevent purple pool water is to maintain, check and clean your pool on a regular basis. Understandably this is not possible during winter, but when spring arrives you should check for any signs of water combination or chemical imbalance in the pool.

By checking the relevant metrics, it’s easy to take steps to prevent your pool water from turning purple. This is much preferable to the alternative of having to treat purple pool water which can take time.


1. Is copper cyanurate dangerous for humans and animals?

Yes, copper cyanurate is dangerous for humans and animals. It’s classified as a hazardous substance by OSHA 29 CFR 1910.1200.

2. Does purple algae in the pool cause the water to turn purple?

No, purple algae in the pool don’t cause the water to turn purple. But due to purple algae, pesticide use might be the cause of your purple pool water.

3. What causes pink pool water?

Unlike purple/lavender pool water, pink pool water is directly caused by pink algae growth in the pool. It is a biofilm so you need a biofilm cleaner to get rid of it.

Final Thoughts

While it might look lovely, purple or lavender pool water is definitely not something you want to see in your swimming pool. Now that you know how unsafe it is to swim in pool water, don’t even dip as much as a pinky in the water until the pool water has been drained, treated, and returned to its natural color.

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I am Donald M. Beyer and I am backyard enthusiasts. I am a homeowner who has been doing DIY projects in and out of my house for many years. From simple backyard lunches to making an old-school pizza oven in my own backyard, I have a lot of experience in turning my backyard into my and my family’s personal playground.

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