Blue Tap Water ?

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flashlight

Senior Member
Location
NY, NY
Occupation
Electrician, semi-retired
While doing monthly checklist for school we work for, their super showed us a problem in one of the science classrooms--the tap water had been running blue !

Unfortunately (or fortunately) it was not doing it when we arrived, but he said it did this from time to time for about a week. A plumber had come in to see if there was any siphoning situation, found none, and then suggested he call an electrician to search for stray current.

Does anyone have any experience with this ? There would have to be current, not just voltage, for electrolysis to occur, right ? From what I remember reading about this problem at marinas, it does not take a high current to cause it. I'm not sure how to go about testing for this, besides the most obvious things (clamp ammeter around water pipe...) and to make things more difficult, the copper plumbing is not easily accessible, even right under the sink.

Would be grateful for any insight on this !
 
Location
NE (9.06 miles @5.9 Degrees from Winged Horses)
Occupation
EC - retired
It can be caused by chemical reaction between the water and the pipe, not just DC current. In other words find out what the city has been treating their water with lately and also have a thorough analysis of the water done. There are certain tests that should be performed on the water...I'll see if I can track them down. CRS

I also don't have a lot of faith in most plumbers understanding the problem. They just simply blame electrolysis due to current flow. I would think one heck of a lot of current flowing to suddenly create blue water. Amp meter sure won't hurt. Find out which faucets were affected as well.

Don't suppose some kids inserted a portion of those Blue toilet tablets behind a faucet screen or two? Surely not.
 

broadgage

Senior Member
Location
London, England
An open or high resistance neutral could certainly cause significant current to flow along copper pipes, and the pipes could be at a slightly different voltage to true ground. That could cause corrosion, BUT in most cases I would expect the OUTSIDE surface of the pipes to be attacked first, leading eventually to perforation of the pipe.

If however two sections of copper pipe are insulated from each other, perhaps by a section of plastic pipe, and there is a significant voltage between them, then current would flow through the water and corrode the pipes from the inside.
Tap water is a poor conductor and the current would be small, even at significant voltages.

I would test for voltage between copper pipes and the service entrance ground connection.
I would also check for voltage between the service entrance ground and true ground. This may be done by driving a temporary ground rod at least 100 yards away, and measuring the voltage between this and the service equipment ground bar.

Do not however assume this to be electrical at all!
Other causes could include acidic water slowly dissolving the copper pipes, or it could be a slow leak between a closed system of heated or chilled water that contains a blue colored corrosion inhibitor, and the fresh water.

In a school dont overlook the chance of pranksters with blue dye or ink !
 

broadgage

Senior Member
Location
London, England
I think that there was another thread on this subject some years ago, also in a school.
Could it be the same place ?
Different electrician called to the same premises, after the problem reccurred ?
 

tkb

Senior Member
Location
MA
Typical, when they can't figure something out whether it is plumbing, hydraulics, electronic problems, blame the electrical system and call the electrician.
I guess it is true, the electrician has to be the smartest guy on the job.
 

mtfallsmikey

Senior Member
Musings from the house plumber..

Musings from the house plumber..

Is this on cold and hot, hot only, cold only? Yes to the acidic water, but I have found bluish-white goo in the bottom of water heaters before, especially if water is both acidic and hard (limestone water). Or, maybe iron in the water??
 

hillbilly1

Senior Member
Location
North Georgia mountains
Occupation
Owner/electrical contractor
I believe it is likely improper chemical balance, I did some control work for a city water department where they would just cut on the chemical pumps in the morning, then cut them off at quiting time. Didn't matter how much water was used during the day. There chemical concentrations were always out of wack.
 

sii

Senior Member
Location
Nebraska
We have a pulverizer that grinds plastic resin and uses water to cool the blades. We started having problems with our "natural" material occassionally coming out blue. It took me quite awhile to figure out it was a water leak behind one of the blades. Our city water is notoriously hard and acidic.

Sorry, I guess this doesn't help you much.
 

gadfly56

Senior Member
Location
New Jersey
Occupation
Professional Engineer, Fire & Life Safety
Copper Sulfate?

Copper Sulfate?

All other things being equal, blue in the water would suggest a process causing the formation of copper(II) sulfate pentahydrate. Electrolysis in the presence of sulfuric acid is one way of producing it. My father used to use it for treating parasites and snails in his fish tanks.
 
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