Note: This podcast transcript has been edited for clarity and length.
Introduction: Blue Stains After a Water Softener?
Hi, my name is Gerry Bulfin. I’m a WQA-certified master Water Specialist and water contractor here in Santa Cruz, California, Northern California. I go deeper into various well water treatment systems and problems each week on our main podcast, but I’m trying to do more of these quick Q&A episodes. We get so many questions daily, and people email, call, and chat with us through our website, so there are always great questions.
This week, John contacted us and said, “We recently had a water softener installed, and now we’re having a problem with blue stains. The company that installed the softener tested our water, and it is not acidic. They said it was not their fault and that they could not help. Have you ever heard of this happening?”
What Causes Blue Stains in Homes With Copper Pipes?
Well, John, yes, we have done it quite a few times. Let me talk about where the blue stains come from. You probably already know this, but blue staining inside, like the blue stains you see on your fixtures, bathtub, or laundry, is a result of copper corrosion. So your house, no doubt, has copper pipes. If you see blue stains, something is corroding the copper pipe. Most of our customers who have problems with blue stains have acidic well water.
So that’s a good reason to check the water and make sure it’s not acidic. If the water is acidic, usually, we find that corrosive water that is acidic is not that hard. Therefore, it’s aggressive water, and you have a problem with copper corrosion, and you get blue stains. The answer is to fix the acidity using our calcite neutralizer, fresh marble, or calcium carbonate.
When It’s Not the Water: Plumbing Problems That Cause Corrosion
You had a water softener installed because your water is hard, and the installer confirmed it’s not acidic. So why the blue stains? In many cases, the issue comes down to plumbing.
Often, the ends of copper pipes aren’t properly deburred before installation. This leaves jagged edges that become corrosion sites. In some cases, too much acid flux is used during soldering, which can also lead to internal corrosion—especially if not cleaned off properly.
The only real fix is to find the affected section of copper pipe, remove it, and have it replaced—ideally by a plumber who carefully deburrs and installs it correctly. If it’s a short section, you might be able to switch to stainless steel flex lines instead.
Here in the Bay Area, we’ve seen widespread issues with copper corrosion due to poor plumbing practices combined with naturally corrosive water. Local agencies have even issued alerts urging better installation practices to avoid this kind of problem.
Is the Softener Itself Causing the Staining?
Another myth that folks often think about is softeners. They think they remove the calcium carbonate and hardness, so now the softener makes the water aggressive or corrosive. In fact, that’s not true. If you have hard water and a neutral pH, meaning it’s not acidic, softening the water is not going to make the water aggressive or corrosive. That’s my experience of what we know.
Protect Your Pipes: Calcite Acid Neutralizer

If your water softener has stopped blue-green staining but copper corrosion persists, it could be a sign of acidic water. Our Calcite Acid Neutralizer gently raises pH using natural calcium carbonate, protecting plumbing from corrosion and blue stains without harsh chemicals or complex maintenance.