corroded copper pipe creating blue green water

Why is Blue/Green Water Coming from my Tap?

Now and then a homeowner will call a plumber with the complaint of “blue or green water coming from my tap.” This water this color is rare. What most often causes tap water to come out blue or green is the corrosion of copper freshwater line plumbing pipes. The discolored water is often accompanied by a metallic taste.

Though many homes now have plumbing made of PVC, CPVC or PEX, there are still homes with copper pipes. Blue or green water happens when the copper plumbing has been recently installed but can also happen if the plumbing is very old and starting to corrode.

Copper corrodes because the pH of the water is too alkaline or too acidic; if the water is full of salts and pathogens; if sand or grit is getting into the water supply and starting to abrade the inside of the pipes and if the water pressure is too high.

Usually, the blue color goes away after the water has been run for a while, but if it doesn’t, the homeowner should contact a plumber or their municipal water company.

Is Blue/Green Tap Water Dangerous?

The one thing the homeowner would want to know is if the blue or green water is dangerous to drink. Copper is an essential mineral necessary for the formation of red blood cells. It helps with the absorption of iron and is an ingredient in many bodily enzymes. However, too much copper is toxic. If so much has leached into the water that it discolors it, the homeowner should probably not drink it, even if it doesn’t have a bad taste. The standard level of copper in drinking water is 2 milligrams per liter.

Copper poisoning is rare, but if it happens symptoms induced nausea, vomiting, and diarrhea. The person also is at risk for problems with their liver or kidneys.

What Causes the Blue/Green Color?

Besides age and corrosion, blue and green water happens when copper plumbing pipes are incorrectly installed. One example is when the plumber uses the wrong type of flux or too much flux on the pipes and fittings. Flux is a material used in soldering.

Another thing that can leach too much copper into the water is to let the water sit in new pipes after the plumbing is pressure tested but before the building is occupied. This sometimes happens in office buildings or apartment compounds, and it is also a sign of poor workmanship.

How to Prevent Blue Water

The prevention of blue or green water is the job of the plumber. They should use only as much flux as is necessary, completely flush new pipes and not allow water to stand in or warm up in new pipes for a long period of time. The plumbing should also be drained if it’s not going to be used right away.

Another answer to the complaint “Blue or green water coming from my tap,” is to have the plumbing system repiped.

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