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Copper Pinhole Leaks


Copper Pinhole Leaks 412 KB /PDF
February 2006
A ToolBase TechNote

Internal pitting corrosion of copper pipes is a rare but costly problem that leads to the
formation of pinhole leaks. Although the factors that cause this problem are mostly unknown,
it is well recognized that the chemistry of the water traveling through the pipes can influence
the formation and propagation of pits.
Pinhole leaks are a major concern to homeowners as they may:

• be costly, given the effort required to find and repair each leak
• result in highly variable amounts of water damage per occurrence
• lead to loss of water resources from undetected leaks in service laterals
• lead to growth of mold and mildew
• result in higher premiums for or cancellation of homeowner insurance

There is also a legitimate concern for consumers that one leak might soon follow another.
Insurance companies often raise premiums or simply do not renew policies, and homeowners
distraught over leaks can reach the point they do not feel comfortable leaving the house
without first turning off the water.
What is a Pinhole Leak?

A pinhole leak is a final breakthrough event of the progressive attack of pitting corrosion
on copper water plumbing. A copper water plumbing system can be in a condition of having
significant damage by pitting corrosion, but not have pinhole leaks.
The challenge is how to
discover pitting corrosion before pinhole leaks develop. Figures 1 and 2 show a pinhole leak
in a copper pipe.
The State of Maryland Task Force to Study Pinhole Leaks in Copper Plumbing defines a
copper pinhole leak as "the perforation of copper tube, pipe or fittings used for domestic
water distribution as the result of pitting corrosion initiated on the interior/waterside surface
with the subsequent leakage of water."
How Many Homes are Affected?

There is no comprehensive source of information on the occurrence of pinhole leaks.
Many utilities and water authorities have collected thousands of reports, submitted voluntarily
by residents who have experienced pinhole leaks. Often, homeowners consider pinhole leaks
as a plumbing problem, and do not report them to their water utility.
Where Do Pinhole Leaks Happen Most Often?

Although pinhole leaks could happen in any copper pipe or tube within a house, the
Washington Suburban Sanitary Commission (WSSC) reported that the majority of pinhole leaks
that their customers had reported were in cold-water, horizontal copper piping.
Most of the leaks were in older homes, and 80 percent of the reports involved homes built prior to
1970.
What is Copper Piping and Why is it Used?

Copper piping has been used for domestic water supply for over 50 years. Since 1963, over 5.3
million miles of copper plumbing tube has been installed in about 80 percent of all U.S. buildings.
Copper is the most widely used material for plumbing systems because of its ease of use,
resistance to corrosion, and resistance to permeation by liquids and gases, which may be sources
of corrosion and contamination.
Copper tubing used for domestic water supply and distribution is manufactured to meet specification
B88, Standard Specification for Seamless Copper Water Tube, established by the
American Society for Testing and Materials (ASTM). According to the Copper Development
Association Inc.'s Copper Tube Handbook:

"All tube supplied to these ASTM standards is a minimum of 99.9 percent pure copper
and silver combined. The copper customarily used for tube supplied to these specifications
is deoxidized with phosphorus and referred to as C12200 (Copper No. 122) or DHP Copper.
Other coppers may also be used."

In addition to copper, there is a maximum of 0.04 percent phosphorus in copper tubing.
The techniques for manufacturing copper piping are the same now as they have been for decades.
Copper (Pitting) Corrosion

There are many forms of corrosion, but pitting corrosion is most likely to culminate in pinhole
leaks in copper plumbing. Pitting corrosion is the non-uniform localized attack of the wall of
copper tube, pipe, or fittings initiated on the interior/waterside surface in the domestic water
distribution system, in which only small areas of the metal surface are attacked, while the remainder
is largely unaffected. Pitting corrosion starts on metal surfaces for unknown reasons, and some
combinations of water chemistry factors allow the process to continue while some do not.
Pitting corrosion can be classified into three types:
Type I pitting is associated with hard or moderately hard waters with a pH between 7 and 7.8,
and it is most likely to occur in cold water. The pitting is deep and narrow, and results in pipe failure.
Type II pitting occurs only in certain soft waters, with a pH below 7.2 and occurs rarely in
temperatures below 140° F. The pitting that occurs is narrower than in Type I, but still results in pipe failure.
Type III pitting occurs in cold soft waters having a pH above 8.0. It is a more generalized form of pitting,
which tends to be wide and shallow and results in blue water, byproduct releases, or pipe blockage.
What Causes Pinholes?

Several studies and research projects have been conducted to determine the possible cause of
pinhole leaks in copper pipes, but no definitive causes have been established.
Some blame it on the chemicals in the water, while others blame it on workmanship and temperature
gradients. The list below illustrates the different variables that are thought to cause pinhole leaks.
These variables demonstrate the complexity of trying to pinpoint the suspected causes.
Possible CausesStudy or ResearchCombination of high pH, low organic matter, aluminum
solids, and free chlorineVirginia Tech, study commissioned by WSSC, December 2004Aggressive
water, poor workmanship, and addition of water softenersUniversity of Florida School of
Building Construction (1997)Workmanship: Excessive use of fluxes; fluxes are corrosive
by their nature
AWWA Research Foundation and DVGW-Technologiezentrum Wasser, 1996Aluminum-bearing
compounds (from concrete pipes, cement mortar lining of cast iron pipes, aluminum coagulant
carryover from treatment plants)Final report on Maryland Task Force on Pinhole Leaks in Copper
PipesCombination of: use of soft waters with low pH; high suspended solids and assimilable organic
carbon content; long-term or periodic water stagnation; low or nonexistent chlorine levels; maintenance
of water temperatures that promote rapid growth and activity of naturally occurring bacteria;
and/or the lack of an adequate monitoring program to periodically evaluate water quality and pipe wall conditionJournal AWWA, August 2001, Vol. 93, No. 8, pp. 82-91Chloramines, which are chemicals
caused by combining chlorine and ammonia (NH3)Virginia Tech, study commissioned by WSSC,
December 2004Water velocity in undersized copper tubes. For tubing sizes normally installed in
home plumbing, the design water velocity should be targeted toward 4 fps.
The greatest effect of velocity occurs where the water is forced to change flow direction, such as at
elbows and tees, but excessive water flow rates can be damaging to the entire plumbing system.
When copper tubing is installed that is too small in diameter for the pressure and flow available, the
resulting high flow rates can erode the protective coating creating areas of bare, unprotected copper.
This effect can result in a high rate of corrosion wherever the protective coating is eroded.A White
Paper Review: History Of Use And Performance Of Copper Tube For Potable Water Service,
Richard O. Lewis, P.E. Lewis Engineering and Consulting, Inc., http://www.wsscwater.com/
copperpipe/letters/copperpipewp.cfmSources of Suspect Pinhole Causes

The suspect causes for pinhole leaks come from different sources.
Element or CompoundSourceAluminum & SilicaCement main pipes; or Coagulant chemicals
added during treatmentSolder fluxPoor workmanshipWater velocityImproperly designed water

Studies have shown that many factors that were thought to contribute to pinhole leaks in copper pipes
have been proven otherwise or have little scientific basis. Some of these factors are:
FactorSourceManufacture of the copper plumbing materialsFinal report on Maryland Task Force
on Pinhole Leaks in Copper PipesElectrolysisSymposium - Copper Plumbing Tube PittingGrounding
of electrical systems/ phone systems to the piping system Harmonic divergence
(the alignment of the planets)Solar flares/sun-spots Cellular phone/radio signalsCheap/inferior
or imported copperRepair Options

Currently, homeowners have several options from which to choose. However, none of the options
address the root cause of the problem; they simply try to correct the symptoms. Most of the options
are also costly. These options include:

• Fixing the leak by application of external solder
• Replacing a small or larger section of tube
• Re-plumbing the entire house (However, even a complete re-plumb with new copper tubing
• does not guarantee that the problem will not recur after a period of time.)
• Re-plumbing and replacing copper with PVC or CPVC
• Coat the inside of existing pipes with epoxy - see the Epoxy Pipe Lining Technology Inventory item
• Purchasing potential cures (of questionable value), such as magnets

Pinhole Leak Prevention

It is difficult to totally eliminate or prevent copper pitting. However, there are a few things
you can do to reduce them, such as:
Examine accessible/exposed copper piping for small, bluish-green stains on the pipes -
away from joints. This can be an indication of a pinhole leak. Call a licensed plumber immediately
at the first signs of leaks. (Bluish-green stains on copper pipes do not necessarily indicate there
is a pinhole leak - they can appear on copper pipes in a damp environment, such as the basement.)
Before purchasing a home, self inspect plumbing (or have a licensed plumber do so), ask about the
plumbing history, and find out how long the house has been vacant, if applicable.
Purchase pipe clamps from any hardware store and install them over pinholes to stop leaks until
repairs can be made.
Have your water tested for pH value. It may be necessary to do this a number of times at several
day intervals, to catch variations. Your water pH should always be higher than 7.
f it isn't, talk to your water department.
Reference Materials

• Task Force Study - Final report on MD Task Force on pinhole leaks in copper pipes
• "Pinhole Leaks in Copper Plumbing."
• http://www.msa.md.gov/msa/mdmanual/26excom/
• defunct/html/
• 10copper.html
• Symposium - Copper Plumbing Tube Pitting
• www.copper.org/environment/NACE02122/nace02122c.html
• J.R. Meyers and A. Cohen, "Pitting Corrosion of Copper in Cold Potable Water Systems",
• Materials Performance, 34 (10), October 1995
• "Corrosion of Copper in Potable Water Systems." Internal Corrosion of Water Distribution
• Systems, 2nd Edition. AWWA Research Foundation and DVGW-Technologiezentrum Wasser,
• 1996.
• VA Tech research: Rushing and Edwards, 2004, and Marshall, 2004.

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[Joseph Tribuzio]

Cool info ROY

However, the article you found states:
" Examine accessible/exposed copper piping for small, bluish-green stains on the pipes -
away from joints."

"... the majority of pinhole leaks
that their customers had reported were in cold-water, horizontal copper piping. "

if you notice in the pictures i posted, the corrosion is taking place MOSTLY at joints and valves of both hot and cold pipes.

So, its not that.

[Jeffrey R. Wicklander]

Were the joints brass? The faucets most likely were. The brass fittings can show corrosion if there is a higher concentration of ammonia in the surroundings as well as/or nitric acid or sulfuric acid.


Jeff

[Joseph Tribuzio]

Originally Posted by jwicklander

were the joints brass? The faucets most likely were. The brass fittings can show corrosion if there is a higher concentration of ammonia in the surroundings as well as/or nitric acid or sulfuric acid.


Jeff

hey now we're getting some where....

[Joseph Tribuzio]

The Inspection was in Crete IL.
There was a water softener system installed.
The home was unoccupied and unofficially "winterized"

I seriously wish i could take as long as i want at some homes.

Damn Realtor always too pushy - i'm adding an hour or two on my time estimate..lol