I see why water heater needs anode rod..HELP

**Lesherp** · 04-04-2021, 03:13 PM

This has nothing to do with our TM but there are a lot of smart people here and maybe someone can help me figure out some things.

I had a leak in my home water line and was surprised and puzzled at what I found. After some research I began to suspect the cause was calvanic corrosion. Isn't that what causes the corrosion I have seen on the anode rod in the TM water heater?

The line running from my house is copper and was attaches to a poly line with a couple of connections of unknown metal. I cant figure out why the edges of the deteriorate connection is shinny. It is puzzling to me that the other connection was not effected. Was it resistant to the effect or was it spared because it was not in contact with the copper?

Can anyone verify that this was calvanic corrosion?

I think the metal may have taken years to start to leak but am suspicious that it accelerated once it began. The month prior to this our water use was zero as we were not there. If the hole had been anywhere close to this large for very long I think we would have lost a lot more water than was shown on the meter for this month. Anyone know if there can be rapid disintegration once a leak starts?

I am planning to replace the corroded parts with brass and hope this will keep it from happening again.

Any insight at all would be appreciated!

oldstick · 04-04-2021, 04:55 PM

Don't know for sure but could that section be galvanized pipe? I know that in the county where we live, a LOT of houses were built during the 1950s-80s or so using all galvanized (iron?) piping. There was found to be some issue with certain minerals in the municipal or well water supplies in the area that promoted corrosion from the inside out and develop leaks over a period of time. After that almost no one in this area used galvanized for water pipes.

But that is in Central GA, not Oregon, so not sure.

**Kidkraz** · 04-04-2021, 06:06 PM

Wow, who ever did that connection did not know what they were doing. The corrosion is actually Galvanic corrosion. "Also known as bimetallic corrosion, is an electrochemical process whereby one metal corrodes in preference to another metal that it is in contact with through an electrolyte. Galvanic corrosion occurs when two dissimilar metals are immersed in a conductive solution and are electrically connected. "
I've rented houses where they used two different types and could see that exact corrosion on the connection and had to educate the property manager of the problem. Some folks don't care if they are not the owner. Hope you didn't have damage other than water leaking.

oldstick · 04-05-2021, 07:06 AM

What is your guess Kildraz? Probably a galvanized steel/iron coupling between the existing brass/copper pipe and the nipple to the flexible plastic line?

Hard to say, from the picture but is it possible the nipple adapter is also actually brass or something? which may explain why it didn't corrode away. Only the iron coupling.

**Lesherp** · 04-05-2021, 09:07 AM

I think the the nipple connection may have been stainless. If you look at the second pic you can see on the nipple end that it has shinny areas. I think it possible the other one is too as you can see that the edges of it where it is corroded is also shinny. That was why I asked if anyone might know if contact of the metals is necessary to cause the reaction. I suspect the deteriorated one was galvanized but the shiny edges puzzle me. The anodic index for copper is -.35, stainless is -.50 and I think galvanized is about -.85; brass is a much better combination with copper at -.40. Another curious thing I did not mention was that rocks were stuck to both as if they were welded on.

The other unresolved question in my mind is how fast this all happened given our water use I mentioned. Kidkraz you seem to have some chemistry knowledge what do you think?

The only damage we may have is to the drain field for our septic as the water flowed across it to surface down below. I'm not sure what went on there.
Thanks for the responses!

tentcamper · 04-06-2021, 09:03 AM

I could be wrong, but it looks like something broke the section out??? was it leaking and you took a pipe wrench to it?? My thoughts are because pipe thread has a taper as it tightens, that maybe it was over tightened and developed stress cracks and the broke later??

oldstick · 04-07-2021, 07:40 AM

I guess the horse is about dead, but was this connection in the ground or in contact with it? Looks to me like all the damage and rock fusion occurred from the outside. That would easily explain it with all sorts of minerals, salts, fertilizer, chemicals, etc. The galvanized coupling would definitely have been the first part to corrode away with ground contact.

**Lesherp** · 04-09-2021, 08:49 AM

The pipe was underground. It went from no leak (0 water use the month before, as we were not there and there apparently was no leak) to the hole you see in a matter of 2 weeks.

It could be that ground contact could have helped but I think calvanic corrosion the main cause. I don't know if the loss of electrons would have left the edges of the hole shinny but that is what I am thinking. I have never seen normal corrosion or rusting do that. The only time I have seen calvanic corrosion is on the anode rod in the TM water heater. The loss of metal seems similar to me.