pin hole leaks

[Jerry Peck]

An interesting read in possible cause of pin hole leaks in plumbing systems:

https://www.mikeholt.com/files/PDF/white_paper_draft-pinhole%20leaks_01.16.20.pdf

(I know, that talks about jails, schools, and thing HIs don't inspect, but those are just "locations" being discussed, what is being discussed on pin hole leaks in copper an steel piping ... and those are also found in homes, which HIs do inspect, so don't disregard the read just because you think it does not apply to you ... it very well could.)

And this has nice pictures too (as well as a good read for the pictures):

https://www.copper.org/environment/water/NACE02122/nace02122c.html

[Lon Henderson]

About ten years ago, I found several pin hole leaks in the copper plumbing at my father-in-laws' townhome. By pinhole, I mean the streams of water were barely the thickness of a hair. (When it was quite in the home, I could hear the faint sound of water spaying on the plastic vapor barrier in the crawlspace and went to investigate.)
The holes did not seem to be associated or aligned with any grounding bond and were in the open areas of the pipes. The plumber and I theorized that maybe the harmonic alignment of the planets caused the problem. (see Table 6 on page 15 of the report):D

The place was built in '74. The plumber and I wondered if cheap copper was used. The corrosion shown in the photos was not present in his townhome. The piping looked like normal copper with some minor mineral buildup at the holes. No new leaks have since appeared, but when the water heater was replaced last year, the copper piping to the utility area was so thin that the plumber had to replace several feet of piping to get to useable pipe. My father-in-law is resisting replumbing the unit. Now, I'm going to go over there with my multi-tester.

[Chris Roth]

About ten years ago, I found several pin hole leaks in the copper plumbing at my father-in-laws' townhome. By pinhole, I mean the streams of water were barely the thickness of a hair. (When it was quite in the home, I could hear the faint sound of water spaying on the plastic vapor barrier in the crawlspace and went to investigate.)
The holes did not seem to be associated or aligned with any grounding bond and were in the open areas of the pipes. The plumber and I theorized that maybe the harmonic alignment of the planets caused the problem. (see Table 6 on page 15 of the report):D

The place was built in '74. The plumber and I wondered if cheap copper was used. The corrosion shown in the photos was not present in his townhome. The piping looked like normal copper with some minor mineral buildup at the holes. No new leaks have since appeared, but when the water heater was replaced last year, the copper piping to the utility area was so thin that the plumber had to replace several feet of piping to get to useable pipe. My father-in-law is resisting replumbing the unit. Now, I'm going to go over there with my multi-tester.


My experience with pinhole leaks in copper pipe was discovered as a maintenance tech at a hotel on the return copper pipe of a recirculation system. The pinholes came from the 90 degree elbows. After the repairs were completed a test was made on the water that entered the facility and gone through the process of ensuring all minerals and whatnot was removed. With that said the water was tested after the cleansing of water to ensure it was pure? Magnesium was the root cause of the destruction of the elbows and not to mention the force of water running downstream through the pipes (speed).

[Jerry Peck]

... destruction of the elbows and not to mention the force of water running downstream through the pipes (speed).

Cavitation is a major cause of damage to copper plumbing pipes (and steel piping, but copper is softer).

https://www.youtube.com/watch?v=0dd6AlyOnfc

https://www.youtube.com/watch?v=gRsvO4Gpnf0

https://www.youtube.com/watch?v=zCE26J0cYWA

[Gunnar Alquist]

"High recovery ball valves are more susceptible to cavitation damage."

"Increasing the valve size tends to make cavitation worse."

For me, both of these statements are counter-intuitive. I'm not saying they are wrong, but I would have thought the opposite. This is, no doubt, due to my lack of education in physics and fluid dynamics.

"The restriction causes the velocity to increase and the pressure to decrease". I know this is true, but I also have a difficult time wrapping my head around it. If I try to cram more stuff into a specific space, it is going to increase the pressure. For example, the air pressure inside a compressor tank is higher than the air pressure outside because I have crammed more stuff into the tank. With fluid dynamics, the opposite seems to be true. I accept this as an axiom (Bernoulli), but it also (for me) is counter-intuitive.

[Jerry Peck]

Gunnar,

The ideal objective is to maintain the interior size of the piping all the way through* as that eliminates 'reductions', which create points of low pressure (Bernoulli), which creates cavitation.

*Applies to cavitation, changes in pipe size are common for other reasons, but with that comes other potential issues, such as cavitation.

Soldered joints (too much solder) are a bad cause of cavitation as solder can build up inside the pipe where one fitting slips inside another fitting, creating a bulge, which creates the low pressure area on the downstream side (Bernoulli), which creates the cavitation (depending upon conditions inside the pipe, flow rate, etc, et al, beyond my knowledge :D ).

Think of a skier going down a ski jump and jumping up and off at the curved up end of the ski jump ... that skier WILL come back down ... and it is not just what they do in the air that they are judged on, but also on if they nail the landing or not.

[Lon Henderson]

How disappointing to learn that Vena Contracta was not her real name, but man, she was fun!

So, gotta say that problems arising from cavitation is not something that I hear about or see in residential plumbing systems. I run into "water hammer" every other year or so, but "gravel" in the pipes or other unusual noise is a never in my experience.

[Jerry Peck]

Most often, in residential plumbing systems, one never "hears" cavitation as the conditions present are not such that it is that bad.

It is more likely that one "sees" the results of cavitation, and only after a plumber who replaces piping and fittings is interested enough to stop and address "hmmm ... why did that happen ... and what does the inside of the pipe and fittings look like" - instead of just trashing the pipe and fittings without looking at them.

[Jerry Peck]

Think of a skier going down a ski jump and jumping up and off at the curved up end of the ski jump ... that skier WILL come back down ... and it is not just what they do in the air that they are judged on, but also on if they nail the landing or not.

Does one just look at the skier who crash landed and go "Ouch! I bet that really hurt.", or does one also look at the ski slope and contemplate that big indentation the skier made when they hit the ski slope butt first at full free fall speed and the gouges their skies made when their skies stuck point first into the slope next to the skiers head, plowing up the snow until the skies snapped?

[Gunnar Alquist]

So, gotta say that problems arising from cavitation is not something that I hear about or see in residential plumbing systems. I run into "water hammer" every other year or so, but "gravel" in the pipes or other unusual noise is a never in my experience.


Most often, in residential plumbing systems, one never "hears" cavitation as the conditions present are not such that it is that bad.

Another reason might be that residential plumbing does not see the level of use that industrial/commercial plumbing would. The prison/jail in Jerry's example might have hundreds of people using plumbing continuously.

[Jerry Peck]

I first heard of cavitation way back when ... in the early to mid 1990s ... when we had a speaker discuss it and show photos of it at a FABI (Florida Association of Building Inspectors - Florida's association for home inspectors) educational conference.

Just one of those things which went in one ear and ... never left out the other ... even though I have never "heard" or "seen" the results of cavitation ... because we, as home inspectors, are not in the habit of cutting open copper piping and looking to see how the piping is holding up.

[Gunnar Alquist]

In "The Hunt for Red October" (Sean Connery, Alec Baldwin, Scott Glenn, Sam Neill, & James Earl Jones), the captain orders full reverse and someone says "We're cavitating Captain!".

That was the first time I heard of cavitation. :cool:

[Jerry Peck]

In "The Hunt for Red October" (Sean Connery, Alec Baldwin, Scott Glenn, Sam Neill, & James Earl Jones), the captain orders full reverse and someone says "We're cavitating Captain!".

That was the first time I heard of cavitation. :cool:

That cavitation they were talking about was because of the sound created by cavitation - it could be picked up on sonar and give away their position.

People with power boats (versus sail powered boats) also know about cavitation; https://www.thoughtco.com/cavitation-causes-and-remedies-2293276 .

I guess it's something I remembered just because it's out of sight and out of mind - the effects of flowing water are well known, such as how smooth rocks get in rivers over time, yet seldom do we think of what flowing water does to the inside of piping ... metal is so much harder and stronger than water ... but so are rocks.

The main saving factor for residential plumbing systems (versus rivers, even jails, prisons, and schools as previously pointed out) is that the water only flows a small portion of the time, most of the time it is just setting still, under pressure and waiting ... and waiting ... and waiting ...