In Greater Vancouver we enjoy an abundant high quality water supply to furnish all of our water needs; drinking, bathing, cleaning, irrigation, fire suppression, commercial processes, etc. Also, we are amongst the greatest consumers of water in the world using an average of 289 gpd/person (1996)[3]. Few if any regions in the world enjoy such an abundant source of high quality water. However, our water is also extremely aggressive, rapidly corroding the materials that we use to convey this water to its outlets.

The corrosion nature of our soft water supply and the piping failures resulting from the corrosive attack by this water has been historically documented. In an article published by The B.C. Professional Engineer, by T. A. Maranda, July (1964) it was stated:

This list of susceptible buildings can be updated to include the many high and low rise multi-residential structures which employ central domestic hot water heating with a recirculation system. Without preventative maintenance, most, if not all, of these buildings will experience the need for a major piping repair or replacement at least once during the building lifetime. Such a repair/re-pipe is a costly undertaking generally requiring a lengthy intrusion of construction workers into people's living or working space. The construction process will also generate noise, dust, and disruption of water service as work progresses.

Knowledge of the causes of corrosion in the water pipe is thus critical in understanding the future implications of decisions made by owners, managers, contractors, and design engineers. There are currently available many alternatives and choices in the manner of repair and the materials to be used. Also, it is possible to treat the water in the building so that corrosion can be reduced thus increasing the longevity of the existing water piping.

[1] AWWA Task Group 2640P Water Quality Goals (E. L. Bean, Chairman), Journal AWWA, 60, 1317 (1968).

[2] "Potable Water Systems--Recognition of Cause Vital in Minimizing Corrosion", J.R. Myers and M.F. Obrecht, Materials Protection and Performance, p 41, Vol. 11, April (1972).

[3] Regional Water Supply Plan, June 1997 (Section 5-6)

The cause of corrosion in its various forms is generally related to the interaction of the selected material with its environment. Poor design and installation are also contributing factors in examining corrosion failures. The study of copper corrosion failures in domestic water pipe installations is complicated by the unique, and changing chemistry of local domestic water supplies. Depending on the source of the water supplied by the local authority, a water source is generally categorized as either "aggressive" or "non-aggressive".

Waters that are characterized as hard waters and contain high dissolved minerals can become aggressive and corrosive when softened. In the typical softening process, insoluble salts are replaced with soluble salts. The resultant water may be aggressive and can be corrosive to piping systems."[1]

Copper is a naturally occurring metal in our environment and can be found to be present in our water, air and soil. It averages 50 ppm in the earth's crust, and about 4 ppb in lakes and rivers. Soil generally contains levels between 2 to 250 ppm with levels of 7000 ppm around copper production facilities. Copper levels in drinking water average 20 to 75 ppb with levels of 1 ppm (1000 ppb) found in many households. Copper is also naturally found in food and drink and is considered an essential nutrient at low levels, with average daily intake of about 1 milligram/day[1].

The EPA (Environmental Protection Agency) in the United States has determined that copper should be limited to 1 ppm in lakes and streams and that drinking water should not contain more than 1.3 ppm[2]. Current Canadian guidelines[3] for copper levels in drinking water are set at 1.0 ppm MAC (Maximum Acceptable Concentration) at the point of consumption.

In high dosages (30 ppm) with exposure limited to once, consumption of copper has been linked to gastrointestinal upsets[4] such as vomiting, diarrhea, stomach cramps and nausea[5]. At a dosage rate of 3 ppm for an exposure of 9 months copper has been attributed to liver damage in infants. The severity of copper intoxication can be expected to increase with both level and length of exposure. Other symptoms of heavy metal intoxication include; mental confusion, pain in muscles and joints, headaches, short-term memory loss, gastrointestinal upsets, food sensitivities and allergies, vision problems, chronic fatigue, etc[6].

Exposures to copper in concentrations greater than the accepted 1.0 mg/l have been reported in drinking water where the copper source is reported to be copper water piping and brass fixtures. Copper will be absorbed over time, and thus first draw water is reported to have the highest concentrations, up to 5.0 or more mg/l. Concentration levels drop with increasing flush time, however depending on the installation, flush times may vary. Higher copper levels are also associated with recently installed copper pipe in new construction or renovations. Copper levels will decrease over time as stable protective oxide layers form resulting in lower dissolution rates.

It is highly recommended that users of any water supply system flush the water for one minute or more when used for drinking. Run the system until the water is at a cold, consistent temperature. Do not drink tepid water or water from the hot water system. Copper levels in recirculated hot water systems may not be acceptable for drinking. In addition to flushing, a good point-of-use drinking water filtration system will improve drinking water quality. Finally, due to the low mineral content and aggressive nature of the local water supply, a personal program of mineral supplements should be considered and consulting a health care professional would be a minimum recommendation.

There is a significant amount of current research involving heavy metal contamination of the environment. Research of copper levels and the impact on fish and marine life populations have been studied. Toxicity and tolerance in mice, sheep, and birds have also been studied. Another concern is how copper can enter and spread through the food chain.

High concentrations of copper have been found in the following locations;

1. Soils around copper production facilities due to deposition of airborne copper dust particulates,
2. Waste disposal and waste waters from mines or other copper production facilities,
3. Sludge waste from sewage treatment plants in water outfalls or landfill sites,
4. Sludge waste spread on agricultural lands.

While absolute tolerance levels for marine, animal and plant life are difficult to quantify, it is generally agreed that these levels are lower than the tolerance levels for humans.

It has been noted that the sewage treatment facility at Annacis Island is unable to remove heavy metals and that copper concentrations at the Iona Island outfall are at levels toxic to marine life. In 1998 there was a reported outbreak of copper intoxication which poisoned a flock of sheep in eastern Ontario. The source of the copper contamination was not specified and was reported to be investigated by the Ontario Sheep Marketing Agency. There are reports that mice populations inhabiting copper mines and around copper production facilities exhibit high levels of copper in their liver and tissue. These mice are food for birds of prey (owls, hawks, falcons) and other carnivorous animals and provide a possible route of metal exposure into the food chain. The effects of this type of exposure have not been determined.

[2] Ibid, p 4

[3] "Guidelines for Canadian Drinking Water Quality, Sixth Ed.", 1996.

[4]"Gastrointestinal Upsets and New Copper Plumbing - Is there a Connection?", Wisconsin Medical Journal, Lynda Knobeloch et al, January 1998.