What Does Green Water in Bathtub Mean? Why and How to Fix

Bathtub water is always expected to be clear and clean before bathing. However, there are some situations where your bathtub water becomes discolored. In this situation, you become confused about what’s causing the discoloration and seek relevant explanations. If you’re in this category, we have the answers.

If you observe unusual green coloration in your bathtub, it may be due to the oxidation of copper and other factors such as contaminated water, mold, and bad water supply. 

This could also be a warning of more severe problems. When this issue arises, it needs to be tackled immediately, as absorption of excess copper into the body can lead to harmful consequences. 

You’ll need to identify the contamination source and use the correct treatment method to fix this issue. Thankfully, it’s easy to treat, and you can fix the problem quickly. We’ll explain what green water in a bathtub means and the possible solutions. Let’s get your water crystal clear again.

Causes of Green Water in Bathtub

The bathtub water green color is unusual and undesirable. But to fix it, we need to know the causes of the green coloration. The following factors are why your bathtub water is green.

  1. Copper Corrosion and Other Metals Oxidation

Copper corrosion is a proven cause of green bathtub water. When copper dissolves inside water, it can cause green coloration. The copper mainly gets into the water due to corrosion resulting from copper plumbing pipes’ natural wear and tear.

This natural copper wear and tear usually happens with old pipes of around 20 years. However, pipes may corrode faster when a pH imbalance and a high concentration of other chemicals are in the water. Also, high water velocity can wear down the pipe’s inner lining, and sand may scrape against the pipe, causing faster corrosion.

  1. Contaminated Water

Check to see if your bath water is in contact with any pollutants. One uncommon pollutant is the presence of pollen grains in the water. These pollen grains are light and can be easily floated by the wind.

Therefore, if pollen is stored in your bathtub, the filter system may be unable to stop it due to its light nature. As a result, you may start seeing some green coloration in the water. Also, copper residues can contaminate your water. High copper levels and other pollutants in your water supply can turn the water green.

  1. Mold

This is a serious cause of green water in bathtubs. Asides from the water discoloration, it poses some serious health risks. These molds can come in different colors, from green, blue, white, or black. Also, mold forming near your wall or basement plumbing can find its way to your water source, turning it green.

  1. Inadequate or Excess Sanitizer 

Inadequate sanitizer in your bathtub can cause green coloration. For example, chlorine is a sanitizer added to water to destroy microorganisms and make water safe. Insufficient sanitizer can cause algae growth, causing the water to go green. Also, excess sanitizer application can cause green watercolor. High chloride levels increase the water’s electrical conductivity, making it corrosive. 

  1. Water Supply

Sometimes, there can be problems with the water supply, which may cause leakage. Molds can accumulate in the supply water, causing blue or green colors in your water.

Fixing the Problem of Green Water in Bathtubs

Fortunately, it isn’t complex to fix this issue. Here are ways you can get your bathtub water clear again.

  1. Run a Check

A quick check on your bathtub’s inner and outer surfaces can quickly help you identify the problem. For example, if the water’s green but clear, it may indicate a high amount of oxidized metals. Observing a slimy surface and cloudier green may mean it’s an algae problem. Whereas pollens are likely to settle at the base of your bathtub, ready to mix at any slight agitation quickly. 

  1. Notify Your Local Water Authority

Whenever you notice green or blue water in your bathtub, ask your neighbors if they have the same issue. If it’s the same issue, it’s a problem with the area’s water supply. After confirming this, call the attention of your area’s local water authority, so they can be aware of the situation and rectify the issue.

  1. Replace Corroded Pipes

Replacing your pipes is a good option to stop the water discoloration if your pipes are rusty. When replacing, ensure it’s a permanent fix. Temporary fixing may seem cheaper now; however, it’s not an effective solution and will increase your expenses in the long run.

  1. Eliminate Mold and Mildew

Getting rid of mold and mildew is simple. You can use borax or baking soda and vinegar to achieve this.

  • Separate the pipes from the water source, and open them.
  • Pour one cup of distilled white vinegar and a half cup of baking soda into the pipes.
  • Stir and leave for about 20 minutes
  • After 20 minutes, pour hot water into the pipe and leave for about 3 minutes.
  • Finally, rinsing the pipe with normal water will help to eliminate mold and mildew entirely.

For borax,

  • Mix one cup of borax powder into a gallon of water.
  • Pour the mixture into the pipe, and leave for about 30 minutes.
  • Afterward, rinse the pipe using normal water, and you’ve eliminated the nasty mold and mildew.
  1. A Fresh Refill

This usually takes more time and is ideal if you have more spare time. Drain the bathtub water thoroughly using a sanction hose or plug hole. After, clean the filter, and use a spa cleaner to spray down the bathtub’s surface.

Usually, algae problems will require just a deep cleaning of the filter cleaner. You can soak the filter for long hours in a chemical rinse to ensure it’s algae-free. Replacing the filter may be ideal if that doesn’t still appeal to you. After cleaning or replacing the filter, refill the bathtub. Refilling can take up to 3 hours, depending on the tub size and the water pressure.


There are various reasons why your bathtub water could turn green. While this is unpleasant, it doesn’t have to be a long-term issue. A simple cleaning of the filters may be the solution to the menace. More comprehensive solutions may require you to perform a fresh refill.

You should note that discolored water can be harmful. While natural elements might make the water colorful, some water coloring may be due to chemicals added to the water to kill harmful bacteria, which can pollute water bodies when discharged into the environment.

Finally, it’s best to prevent this issue from occurring. Always cover the bathtub when not in use, and add enough sanitizer to the bathtub’s volume. You can check this by testing the water regularly. Also, clean the filters regularly, and replace worn-out filters on time.

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