Tap Water Yellow After Repairs

[Timothy Pruden]

After I accidentally broke the cold water supply line to my bathroom sink due to corrosion, I was eventually able to learn how to solder copper pipe, and successfully replaced both lines without any leaks! Unfortunately the tap water (both lines) has since taken on a noticeably yellow tint, which seems to clear up after running the water for 10 to 15 seconds, but then returns the next time the faucet is used. I'm curious as to the possible source of discoloration and potential solutions. It might be relevant to note that there was a vein of black sediment, running through both supply lines, which had concreted prompting the replacement of both pipes.

 

[Reach4]

If you draw a glass of cold water, is it noticeably yellow? That is pretty wild. How much galvanized steel remains, and did you add any? Is this city water?

If you add a bit of chlorine bleach to a glass of yellow water, does the yellow go away? I don't know how much would be needed. A drop, 1/2 teaspoon?? Anyway, the thinking is that ferrous iron would convert to ferric iron (rust) which would precipitate out of the water. If the yellow was something like tiny clay particles, the bleach would not get rid of the yellow.

 

[Sponsor]

 

[Timothy Pruden]

If you draw a glass of cold water, is it noticeably yellow? That is pretty wild. How much galvanized steel remains, and did you add any? Is this city water?

If you add a bit of chlorine bleach to a glass of yellow water, does the yellow go away? I don't know how much would be needed. A drop, 1/2 teaspoon?? Anyway, the thinking is that ferrous iron would convert to ferric iron (rust) which would precipitate out of the water. If the yellow was something like tiny clay particles, the bleach would not get rid of the yellow.

City of Greeley, in Colorado. I see no precipitation upon adding chlorine bleach, and the water stays noticeably yellow. The supply lines go from copper, to a brass elbow, to 4" galvanized steel, to a brass coupling, to pex, and then of course to the faucet itself. Both hot and cold are yellow. I was hoping at first it was somehow caused by the flux, when I soldered the copper and brass together, but it doesn't make sense to me that it would last this long (now a week) if that were the case.

 

[Dj2]

If you have any galvanized iron pipes or connectors, you can expect rusty yellow water. It would be fairly easy for you to replace those pipes, even if you have to open walls.

 

[Jadnashua]

Get rid of the galvanized...it never was a great idea in potable water systems. See if that improves things.

It's not uncommon when the water is shut off, drained, then turned back on to flush out some crud...but, it normally doesn't last that long.

 

[Timothy Pruden]

The galvanized steel on the cold side was the pipe that originally busted. It broke at the threading where it met the original brass elbows inside of the wall. When I tore everything apart, I discovered that both supply lines were corroded and had wall-like veins of black cemented sediment coursing through them, and so I replaced everything almost like it was originally. The one thing I changed was the couplings connecting the pex to the galvanized steel; whoever put in the supply lines last time used these weird chrome elbows that worked like female compression fittings where the pex connected and also had female thread connecting to the galvanized steel, so I switched over to the correct brass adapter to go from the 1/2" galvanized to the 1/4" pex. The only pipes that aren't brand new since the repair, are the copper pipes coming down inside the wall (the sink in question is in a basement lavatory), and the pex tubing because I couldn't get the pex detached from the faucet.

 

[Jadnashua]

Galvanized piping gets damaged when it is threaded. Galvanized piping does not last forever. Potable water has oxygen dissolved in it. Iron and oxygen will create iron oxide (rust). Not much you can do about it. It is never a great idea in a potable water system. It can work in a closed heating system because after a short period, the water used to fill the system, all of the oxygen is used up...so, often, they don't even bother with galvanized, and use plain steel pipe. A potable water system is constantly adding dissolved oxygen, and things will rust. Shutting off the water, draining the pipes, then turning things back on can dislodge a lot of crud, and take awhile before it all gets flushed out. In the process, it may have exposed fresh iron, so more can now rust.

 

[Timothy Pruden]

Galvanized piping gets damaged when it is threaded. Galvanized piping does not last forever. Potable water has oxygen dissolved in it. Iron and oxygen will create iron oxide (rust). Not much you can do about it. It is never a great idea in a potable water system. It can work in a closed heating system because after a short period, the water used to fill the system, all of the oxygen is used up...so, often, they don't even bother with galvanized, and use plain steel pipe. A potable water system is constantly adding dissolved oxygen, and things will rust. Shutting off the water, draining the pipes, then turning things back on can dislodge a lot of crud, and take awhile before it all gets flushed out. In the process, it may have exposed fresh iron, so more can now rust.

Just to be clear; Are you suggesting the newly installed galvanized pipes are potentially the source of the discolored water due to rust? If so, I'm assuming there is a viable brass nipple, or something I can use to replace these steel nipples with...

 

[Jadnashua]

The pipe is galvanized, then cut and threaded...those areas are NOT galvanized and rust will start there. Depending on the quality of the plating, yes, the thing could be the source of the rust even when new (say Chinese, cheap import?). It will rust more and more over time, and eventually fail like the original one did. Yes, there are brass nipples, and you can make one any length if you use threaded fittings on plain copper pipe, but you'll need to be able to solder.