Why is Water Staining Green or Blue and How to Remove It

Why is Water Staining Green or Blue and How to Remove It
If you see green or blue stains in your home’s sink, the culprit is probably corrosion of your plumbing, which is leaching copper into your water. Corroded copper turns blue/green.

This problem is often caused by low pH water, which eats away at copper pipes and fittings. This can also be a warning of more serious issues.

The effects on your home - and your health - will depend on the level and source of the issue.

In order to fix the problem, you’ll need to identify the source of the contamination and apply the appropriate filtration treatment solution.

What causes blue or green water stains?


Blue or green staining is most often the result of corroded copper or brass fittings. (Brass is an alloy of copper and zinc.) When copper dissolves in water, it can tint the water blue, and leave blue-green stains on your fixtures.

Sometimes, new plumbing is the source of the metal in your water. New copper pipes can leach copper into the water, depositing blue-green stains until an oxidized coating builds up inside of the pipe. This problem usually takes care of itself within the year.

But if your plumbing isn’t brand new, it’s more likely that your home has especially corrosive water. If your water has low pH, also known as acidic water, it can eat away at your plumbing and fixtures over time.

It’s also possible the corrosion is a result of your water’s chloride levels. High chlorides increase the electrical conductivity of water, making it corrosive to metal plumbing. If you live in a coastal area, you may see high chloride content from saltwater. Elevated chloride levels can also be the result of salt deposits in groundwater, or pollution from sources such as road salts or septic systems.

How can you know what is causing your stains?

If you have pinhole leaks in your copper plumbing, pitting in your pipes, or blue green stains on plumbing fixtures, these are likely signs of corrosive water. Water with a lot of dissolved copper in it may also taste or smell bad or have a blue color.

While these clues point to corrosion and acidic water, you should also be alert to the possibility of lead in your drinking water, which leaves no trace but may be another hazardous contaminant resulting from plumbing corrosion.

While symptoms such as colored stains and odors can indicate probable types of water contamination, the best way to know exactly what is lurking in your water is to use a water test.

A water test can tell you if your water is outside the normal pH range of 6.5-8.5, whether there is copper in the water, or if your chloride level is too high. If the measure of Total Dissolved Solids (TDS) in your water is above 250 mg/L, it may be an indication of elevated chlorides.

If your water comes from a private well, you are responsible for the testing and treatment of your water supply.

Read more about well water safety and treatment

Before investing in any filtration solution, it’s crucial to test your water to find out exactly what’s in it so that you can choose the most effective treatment.

Read more about testing your water

Purchase a water test

What is corrosive water and how does it affect your home?

Water that has a pH of 6.8 or less is considered corrosive and can cause damage to any metal surfaces it comes into contact with. The lower the pH, the more acidic the water. Each .10 of a point below is exponentially more corrosive.

If your water’s chloride level is above 250 mg/L, it exceeds the EPA’s maximum contamination level for chlorides and is also considered corrosive.

The effects of corrosive water can include:
  • Leaching of copper or iron from inside of the piping and depositing of blue-green (copper) or rust-colored (iron) scale on sinks, tubs, and other plumbing fixtures.
  • Damaged metallic finishes
  • Shortened fixture and appliance lifespans
  • Stained laundry
  • Formation of pinhole leaks in plumbing over many years
  • Bitter, metallic taste of water


Are blue or green stains from water a health risk?

Because the blue or green stains in your water are symptoms of corrosive water, the health risks are related to both the corrosive nature and the contaminants.

Health risks of low pH water

If your water is acidic, it may be high in not only copper, but also lead, arsenic, nickel, cadmium, chromium and zinc. Heavy metal exposure can lead to diarrhea, nausea and vomiting, abdominal pain, chills, weakness, shortness of breath, suppression of the immune system and organ damage.

It’s not recommended to drink acidic water , as it can lead to heavy metal poisoning or toxicity. It may also erode tooth enamel.

Severely acidic water - with a pH of 4.5 or less - may slowly erode tooth enamel and lead to tooth decay.

Health risks of copper in water

When it comes to copper in your water, your body needs some to stay healthy, but too much is harmful.

Excess consumption of copper can cause vomiting, diarrhea, stomach cramps, nausea, liver damage, and kidney disease. People with Wilson’s disease and babies under one year old are extra sensitive to copper and are not able to eliminate excess copper easily.

Drinking water with more than 1300 micrograms of copper per liter of water can be a health risk for everyone. (1 microgram per liter = 1 part per billion (ppb).

Copper can be harmful to animals as well, particularly fish.

Health risks of chloride in water

Water with chlorides with higher than 250 mg/L may taste salty and smell unpleasant.
If your chloride level is higher than this, excess consumption can complicate existing heart problems and contribute to high blood pressure.

How do you treat corrosive water?

Once you’ve tested your water to confirm the source of your issue - whether low pH, high chlorides, or copper - you can choose the most effective solution to treat it.

Low pH water - Neutralizing System

You can raise your water’s pH level with a pH Neutralizing System.

Tier1 pH neutralizing systems utilize a mixture of calcium carbonate and magnesium oxide, two neutralizing agents that will raise the pH level of your water while not producing a solution that becomes predominantly basic.

System includes both ¾” and 1” water line connections and mechanical components necessary for standard installation. Installation manual is also available online.

This system is available in two sizes:

1-3 bathrooms
4-6 bathrooms

Elevated Chlorides or Copper - Reverse Osmosis System

It’s important to note that neither boiling water nor chlorine disinfection will remove copper from water.

For effective treatment of not only chlorides and copper, but also a long list of other contaminants including arsenic, lead and total dissolved solids, you can install an undersink reverse osmosis system.

Reverse Osmosis System

You can treat corrosive water and green or blue stains

When you’re dealing with the blue-green stains of corrosive water, Tier1 offers safe, reliable treatment options to solve your problems.

If you want to ensure your water is free of other contaminants, it’s always a good idea to test it to find out exactly what’s in it in order to choose the most effective treatment solution.

If you’d like a personalized recommendation for your home, the Technical Support Team at Tier1water.com is available to chat or answer your call.