Blue and Green stains from my water, what causes them?

It amazes me when I step into a home where someone has lived for a long period and I see blue or green stains in sinks, tubs, and toilets.

"When did you first notice the stains?" I will ask.

"Oh, they have always been there." is a reply I hear much to often.

Blue and green stains are almost always the result of copper depositing on surfaces of water using fixtures in your home. There are three major causes:

1. You have naturally acidic water from your well or municipality. Acidic water eats the copper pipes from the inside and leaves deposits wherever water can sit and dry off. In this case you will need to have a whole house neutralizer installed to raise the pH.
2. Your water district is adding chlorine to the water to keep it micro-biologically safe. Chlorine can oxidise the inside of copper pipes and that water can leave deposits wherever it has a chance to sit and dry off. A whole house carbon filter can remove the chlorine, but if your home is supplied with a copper line from the main, that copper will have a chance to oxidize because it is before the carbon filter. You may get an improvement, but in this situation, you may never be able to remove all the copper.
3. The plumbing or some or all of the electrical system is mis-grounded. Enough electricity flowing along copper pipes can peel atoms of copper off of the pipe and leave them in the water where it will have a chance to leave a stain when that water is able to sit and dry. If you suspect this, don't call a plumber, call an electrician.

Why should you care about blue and green stains? Because the copper being deposited in places where it makes stains used to be the inner part of your copper pipes. Unless you have naturally occurring copper mineral deposits coming up from the water in your well, blue and green stains are a sign that your copper plumbing is thinning out and will eventually leak. It may leak in the basement, but it may also leak in a wall or somewhere else. If you see blue and green stains, you should at least get a water test so that you can begin to determine what the cause is.