Why is My Pool Water Purple? Common Causes and Solutions

Have you ever noticed your pool water taking on a mysterious purple hue? If so, you may be wondering why this unusual coloration has occurred. Purple pool water can be caused by various factors, ranging from chemical imbalances to external contaminants. In this article, we will delve into the different reasons why your pool water turns purple and provide you with some practical solutions to address the issue.

The Role of Copper in Purple Pool Water

One common culprit behind purple pool water is the presence of copper. Copper, a metal commonly found in some pool chemicals, can cause water to take on a purple tint when it oxidizes. This usually happens when the pool’s pH level is too low or when copper-based algaecides or ionizers are used excessively.

In addition to low pH levels and the use of copper-based products, other factors that contribute to the presence of copper in pool water include:

  • Corroded metal fittings or plumbing
  • Leaching from pool equipment or heat exchangers
  • Chemical imbalances
  • Unbalanced or excessive use of copper-based algaecides

If copper is the cause of the purple hue in your pool water, it is important to take immediate action to rectify the issue and prevent further discoloration.

Bacterial or Algal Infestation

Another factor that can contribute to purple pool water is the presence of certain bacteria or algae. Some specific types of bacteria or algal infestation can result in your pool water appearing purple. This can occur when the pool’s sanitization levels are not properly balanced or if organic matter builds up excessively.

To determine if bacteria or algae are responsible for the purple coloration, you can perform a simple test. Take a sample of the purple water and add a small amount of chlorine. If the water clears up, it is likely an indication of bacteria or algae being present.

Preventing and addressing bacterial or algal infestations is crucial to maintaining clear and healthy pool water. Regularly testing and maintaining appropriate sanitizer levels, as well as properly balancing the pool’s chemistry, can help prevent these issues.

Effects of Metal Oxidation

When metals in the pool water oxidize, they can contribute to the development of purple shades. Copper is not the only metal that can cause this discoloration; iron and manganese are known culprits as well. These metals may enter your pool water through various sources, such as corroded metal pipes, well water, or certain pool chemicals.

To identify whether metal oxidation is causing the purple color, you can perform a simple test using a sequestering agent. This agent binds to the metal ions and if the water becomes clear, it implies that metal oxidation is the root cause.

To prevent metal oxidation and subsequent purple discoloration, consider the following steps:

  1. Regularly check and balance your pool’s pH levels
  2. Ensure the proper filtration and circulation of water
  3. Use a sequestering agent to prevent metal ions from precipitating

External Factors and Contaminants

Purple pool water can also be a result of external factors and contaminants that find their way into your pool. Some of the common offenders include:

  • Leaves, berries, or flowers falling into the water
  • Dye from clothing or towels
  • Pollen or other plant matter

While the presence of external contaminants may seem harmless, they can cause the water to take on a purple tint over time. Regular cleaning and maintenance, including skimming the water’s surface and cleaning filters, can help minimize the impact of external factors on your pool water color.

Issues with Pool Finish or Liner

In some cases, the purple color of your pool water may be a result of issues with the pool’s finish or liner. If the color change is accompanied by other signs of damage, such as peeling, cracking, or bubbling, this could be a clear indication of a problem.

Common causes of pool finish or liner issues include:

  • Chemical imbalances
  • Damage from excessive sun exposure
  • Improper pool maintenance

Addressing these issues may require professional assistance. Consult with a pool specialist to inspect and repair any damage to your pool finish or liner, which may be causing the purple discoloration of your water.


When faced with purple pool water, it is essential to identify the underlying cause to effectively address the issue. Whether it is copper oxidation, bacterial or algal infestation, metal oxidation, external contaminants, or problems with the pool’s finish or liner, understanding the root cause will guide you in implementing the appropriate solutions.

By maintaining proper pool chemistry, regularly monitoring and balancing the water’s pH, and promptly addressing any issues that arise, you can enjoy crystal-clear pool water that remains sparkling blue all season long.