Blue-green pieces flowing out of hot water pipe

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FixingIt

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Some time ago, maybe 6 months or so, I noticed the hot water flow in my bathtub starting to slow. It continued to slow for a few weeks, until I finally gave up and removed the cylinder (it's a single handle) and cleaned it out to investigate. In the back, wedged into the check valves, were some blue-green pieces. I cleaned them out, reassembled it, and it worked again when I next filled the bath. However, when I went to take a bath the next time after that, it had slowed to a dribble on the hot again.

To make a long story short, this has since happened again and again, with cleaning the chunks out of the valve resulting in one more filled bath of good flow before it would clog up again. I finally went down to my utility sink in the basement (this is a single story ranch home, with copper plumbing on the supply lines and a water softener as we have very hard water where I live), and began to flush things out there. Between the disconnected supply hoses for the laundry machine (which I haven't used in some time) and the faucet, I managed to flush out quite a bit of the material from the pipes, but it keeps coming!

Experimenting a bit, I've found that the best way to try and flush it out is to cause a water hammer by rapidly turning on/off the quarter-turn boiler drain valves (I often turn off the hot water in the bath very rapidly). I have numerous arresters in the home; a few of the older "open air" ones, which I believe are now only on the cold lines to the toilets, a several of the newer kind with a plunger inside to keep them from filling with water over time. All of the latter were added by me in the last few years, but I suspect are unrelated to the problem, as I have also added some to the cold supply lines and have not experienced any problems there.

I think the problem lies much further back, as it's affecting all faucets that use the hot water--which points me toward an issue relating to the water softener or the water heater, and possibly exacerbated by the thermal shock of hot water after the pipes have cooled or the physical shock of a water hammer. However, I'm not sure what to look at first, so I've collected some samples by sieving out the pieces that are flowing out. I'm also at the tail end of a kitchen remodel, and had some of the old riser pipe for the kitchen faucet supply lines that I replaced, so I cut a sample off of each. I'm not sure which was hot, but I strongly suspect it was the one on the left in the picture, due to the color similarity with the matter discharged. However, I didn't notice any large chunks in the pipe, but that might be due to the fact that it was riser pipe (the particles that come out float in water, so I suspect if they're accumulating in the pipe, they form at the top of the long horizontal runs).

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Higher resolution images of these can be found here for the former and the latter.

So, any ideas on how to fix this, or what is even causing the problem in the first place? :confused:
 
Does your water softener treat only the hot water or Both H&C?

The green is usually caused by oxygen in the water causing copper oxide.
But those chunks are not from that. Could be from the salt from your water softener.

I would start there. Here's an article I found that might be helpful.
Don't believe every thing you read on the internet.

How to treat copper pipe corrosion
 
I just double checked, and all inside cold lines are also softened with one exception--the kitchen sink! It's quite possible that this is an issue on the cold lines as well, but I've never seen anything come out of them, and my "canary in a coal mine" valve, the bathroom tub, has never been plugged on the cold side and shows no issues when I inspect it to clean out the hot side. So that could explain why the riser pipe to the kitchen sink looks so different, being the only cold pipe I've looked at is unsoftened.

Looks like I've got a lot of homework to do, and tests to perform on my water. One other thing I noticed while looking at the pieces that washed through though is they are smooth and often tinted a copper-color on one side, seeming to imply that that was the side that they "grew" from. However, this makes it look like they were growing on the outside of copper pipe, not the inside. Perhaps it's corroding on the outside of the lines feeding into or from my water heater?

I own a inspection cam, so I may turn off and drain the heater and take a look inside it. I'll also look and see if there's any indication of corrosion in the outflow from the water softener, which might let me narrow it down between the two.
 
Back in the day we used to run a hard water line to the kitchen sink for drinking only. Softeners used more salt back then and the water had sort of a flat taste because of it. If you had been drinking well water for years then added a softener, the soft water would have a very different taste.

I have never seen light green chunks like you showed in your image so I can't comment on where they may have come from. What I would like to know is the PH of your water.
 
I've tested the pH, but unfortunately the only thing I had on hand to do so, a color-changing paper, is made for a wide range and not to give accurate readings in the narrow range you'd expect for tap water. The color did match closely with the color for a pH of 7, but I expect it could easily be +/- 0.5 or even further.

Also, after repeated flushing, I think I finally got all of the chunks out of the system via my utility sink. I took out the valve cylinder in the bathtub, and bolted a temporary PMMA cover over the housing. I turned the water back on at full blast, flushing both the hot and cold lines to the tub simultaneously (I have no ball valves on the supply lines to the tub to turn off just its cold/hot--yet). Putting the valve back in, things seem to be working even after filling the bath once and testing it again.

Unfortunately, and because of the problem being resolved for now, I don't know if I can determine the cause, unless it starts happening again. I'm still going to take a look with my inspection cam, probably later this week, both from where the water softener is connected, and within the hot water tank as I really need to install an expansion tank for it (the T&P valve will discharge water during reheating after filling my bathtub). I'll report back with my findings.
 
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