Copper corrosion –
the health and
physical effects
What is Copper?
• Copper is a metal that exists in the
environment as a mineral in rocks and soil.
• It is commonly found at low levels in natural
water (0.05 to 0.6 typically)
• It is also an essential trace element that is
required to maintain good health.
• Has been used in plumbing >4000 years
What are the potential health
effects of copper?
• The normal adult requires approximately 2 to
3 mgs of copper / day to maintain good
health.
• Consumption of high levels of copper can
cause nausea, vomiting, diarrhoea, gastric
complaints and headaches.
• Long term exposure over many months and
years can cause liver damage and death.
What are the potential health
effects of copper?
• The symptoms of nausea, vomiting,
diarrhoea, gastric complaints and
headaches are similar to many other
ailments and may not be attributed in the
first instance to copper toxicity.
Australian Drinking Water
Guidelines
Australian Drinking Water Guidelines sets two
levels for copper:
• 1mg/L for aesthetics to prevent taste and
staining problems; and
• 2mg/L to prevent any health related
problems
• The taste threshold for copper is 3 to 5 mg/L
• Acute gastric irritation may be observed in
concentrations above 1.3 mg/L.
How does copper get into drinking
water?
• The primary source of copper in drinking
water are corroding pipes and fittings.
• Signs of high levels of copper in drinking
water include a metallic taste or blue to
blue-green stains around sinks and
plumbing fixtures.
How does copper get into drinking
water?
• The long term safe performance of copper
pipe is dependent on the establishment of
a natural protective internal surface film of
copper oxides and copper carbonates.
• Through either physical, chemical or
microbiological interference with this
surface film corrosion of the copper pipe
begins.
Natural protective internal surface
film
How does copper get into drinking
water?
• AS 3500.1 states ”Copper and copper alloy
pipes and fittings shall be installed in
accordance with installation requirements of
AS 4809”.
• AS 4809 states “the service life of copper
pipe installations may compromised if used to
convey water that falls outside of ADWG
particularly in terms of pH, Alkalinity, chloride,
sulphate and residual disinfectant.”
Ways copper pipe can corrode
• Copper pipe can corrode:
– Externally
– Internally
Causes of external corrosion of
buried copper pipe
• Exposure to abnormally corrosive/aerated
soils and/or fill
• Galvanic corrosion associated with
exposure to dissimilar metals
• Faulty design and workmanship (fluxes)
• Stray electrical currents.
External corrosion
Causes of internal corrosion
• Internal corrosion of copper water pipes is
a highly complex issue that is not yet fully
understood and is still subject to ongoing
research.
• It can occur in both treated and untreated
water supplies in both large and small
supplies and from both surface and bore
water sources.
Internal Copper Corrosion
• There are four main mechanisms through
which a copper pipe or fittings can cause
internal corrosion problems for consumers.
• They are primarily caused by either
physical, chemical or microbiological
interactions on the copper pipe or fittings.
Erosion-Corrosion
Erosion corrosion is a form of pipe failure
caused by excessive velocity, dissolved
gases or the presence of particulate matter.
Pitting corrosion
• Pitting (non-uniform) corrosion is usually
associated with water composition issues,
particularly but not exclusively with low pH
and low alkalinity parameters.
• Can affect both hot and cold water supplies
more recently recirculating HWS.
• Pitting corrosion is seldom associated with
elevated levels of copper at taps.
Pit corrosion chemistry
Pitting corrosion
Cuprosolvency (copper dissolving)
• Generally involves a slow rate of uniform
corrosion where Cu ions are retained in
solution rather than precipitated out.
• It is characterised by elevated levels of
dissolved (soluble) copper
• More prevalent in new pipes with low pH
<7.0 and relatively soft or hard water.
Blue water corrosion
• Blue water is characterised by blue-green
colouration in water when first drawn from
a tap.
• The blue water is a result of a finely
divided insoluble flocculent of copper
corrosion by-products suspended in water.
• It is more frequently observed in pipes with
patterns of low use
Blue Water Corrosion
• It almost exclusively occurs in cold, soft,
poorly stabilised or low alkalinity waters.
• Believed to be microbiologically induced
corrosion (MIC)
• MIC linked to presence of soft
carbonaceous water producing biological
film in pipe
Factors that affect the population
exposure to copper in drinking
water
Water composition
• Water composition drastically affects copper
release particularly if the water composition that
falls outside the range nominated by ADWG most
notably in terms of :
• pH
• Alkalinity
• Chloride and Sulphate levels
• Residual disinfectant levels
ADWG recommend pH 6.5 to 8.5 to reduce
corrosion risk
Factors that affect the population
exposure to copper in drinking
water
Stagnant contact time
• This is a major contributing factor.
• Can lead to high increases in copper
concentrations depending mainly on water
composition and on the age of the pipe.
Factors that affect the population
exposure to copper in drinking
water
Age of copper piping
• Studies conducted in Germany and else
where show that copper by product
release from the pipe to the water
(cuprosolvency), is much greater for new
pipes rather than for old copper pipes.
Factors that affect the population
exposure to copper in drinking
water
The design and installation procedures
• The liberation of copper by-products can be
influenced design parameters such as:
– Presence of high velocity flowing water,
– Pipes in contact with different types of soil or
concrete,
– Differences in temperature,
– excessive number of bends in the network,
– electrical grounding contacts,
– stresses built up in the piping system,
Factors that affect the population
exposure to copper in drinking
water
The extent of use of copper in the
distribution network
• The use of copper pipe in domestic
installations has waned still very common
in HWS, commercial and government
projects.
• Germany actually prohibits the use of
copper when the water composition is
prone to copper by product release.
Factors that affect the population
exposure to copper in drinking
water
Drinking habits of the population
– the amount of water consumed
– the time at which people drink water from the
tap,
– the location of the tap,
– the use of water from the HWS.
affect the total copper ingested.
Case Studies
Case Study One
• 10 children in western NSW high school
became ill after drinking water from bubblers
after summer break 2004.
• Elevated Cu levels of 5.7 to 42.3 mg/L
• pH as low as 4.3 recorded as WTP offline.
• WTP brought back online and flushing of
mains resulted in Cu levels dropping to 0.67
to 1.2 mg/L.
Case Study Two
• September 1993 15 children in SW
Sydney became ill at a tennis clinic after
consuming water drawn from a distribution
system that supplies potable water to a
semi-rural township.
• In response to a suspected outbreak of a
waterborne illness the PHU investigated
Case Study Two
• Further testing revealed Cu levels in water
ranged from 3mg/L to l7mg/L.
• PHU determined elevated CU levels most
likely resulted from a combination of factors:
– soft, acidic water enhancing leaching of copper
into the water reticulation system; and
• the external tap not being flushed for some
time before the tennis clinic.
Case Study Three
• Urban residential property provided with
reticulated water supply.
• Complaints of illness (nausea and
vomiting) and blue/green discolouration of
bathroom fixtures.
• Detailed investigation by Water Utility
undertaken.
Case Study Four
• Rural property, plastic water supply pipes, plastic
rainwater tanks, colorbond roof supply.
• Following installation of recirculating solar hot
water system.
• Elderly male presented with symptoms of nausea,
vomiting, diarrhea, gastric complaints and
headaches Cu blood levels 32 micromol/L (normal
11-22)
• Analysis of copper levels in drinking water showed
levels of 0.86 to 3.15 mg/L in both hot and cold
supply
Implications for Public Water
suppliers
• Routine monitoring through Drinking Water
Monitoring Program (DWMP) should not
detect the presence of Cu in internal water
mains.
• In areas where soft acidic water is present
advice from water utility should be given
about the potential for copper corrosion to
be present.
• EHOs have a vital role to play.
Implications for Private Water
Supplies
• Private water suppliers are now required
to have in place their QAP.
• The issue of copper corrosion and the
potential impact on human health may be
poorly understood by the business
operators and may need guidance.
• EHOs can play an important role in public
education
The Australian Plumbers Handbook
says
• The composition of untreated supplies and
bore water should be examined to ensure
compatibility with copper prior to
installation.
• Untreated tank water may not be
compatible with copper due to the lack of
stability and potential microbiological
variability.
Public information on Copper
Corrosion
• Various State & Territory Health Departments
and Large Water Utilities have provided
advice on the health risks of copper corrosion
via fact sheets and web based advice.
• Typically the advice is based around flushing
of water mains or the installation of water
filters or pipe replacement.
• Flushing not a viable long term option
Conclusions
• The whole issue of copper corrosion is
very complicated and no-one fully
understands it yet, despite a lot of
research effort.
• The health effects of copper toxicity are
not well understood due to general nature
of symptoms (confusion with other
potential ailments eg: FBI etc.)
Conclusions
• Water quality varies widely across the state
as such Cu corrosion rates will vary.
• WSUs do not test consumer mains for water
quality
• EHOs have a major role to play in supporting
the water supply authorities and private water
suppliers and consumers in understanding
issues around copper corrosion.
Future Work
• There needs to be more work undertaken
to establish the links between presenting
illnesses and the presence of elevated
copper blood levels to confirm actual
cases of copper poisoning.
Acknowledgements
Warren Matthews PHU NSW Health
Dr Sandy Leask & Josh Tickell from Water
Unit NSW Health
Questions?