From the construction of the very first water network, engineers have searched for the best pipe material. Over time, it appears that all materials end up leaching into the water, and this can have consequences for our health, and the environment’s. These days, around 90% of our house water pipes and connections are made of copper. How dangerous is this metal?
In 2017, farmers discovered just how life-threatening copper can be to animals. At a farm in the Netherlands, calves drank water supplied by a network of old copper pipes. They died 48 hours after the first symptoms showed up. The same thing happened that year at another farm – animals drank water with a high concentration of copper residues, and died. Cows need copper, but too much can cause fatal liver damage.
When cows ingest copper over a long period of time, it builds up in the body, particularly the liver. At first, the animals display few visible symptoms. However, once liver damage occurs, a large part of this copper is released. The result is anemia (a lack of healthy red blood cells to transport oxygen throughout the body), loss of appetite, jaundice, and nervous system damage. The animals deteriorate fast and then die. But copper isn’t just a problem for animals. Too much of this metal is also detrimental to human health.
Out of the 6 million house connections in the Netherlands, around 5,400,000 are made of copper, usually with taps and fittings made of brass.
Copper has been used for millennia. Archaeologists have discovered copper objects dating from 10,000 years ago. The Romans first came across it in Cyprus, which explains the name ‘aes cyprium’, or ‘metal of Cyprus’. Later this became ‘cuprum’, from which the word ‘copper’ is derived. Today Chile, China, Peru, the Democratic Republic of Congo and the United States are the top global copper producers.
In the right quantities, copper is an essential nutrient.
The body needs it to form and maintain connective tissue and bones; it is an important component for a strong immune system and for blood clotting. Copper is involved in the transport of oxygen throughout the body, and even determines hair color (pigmentation). It plays a role in cardiovascular health and hormonal balance. The body uses copper to produce enzymes that protect cells from free-radical damage.
Copper deficiency has been linked to mental disorders, impaired central nervous system, and fragile bones. However, it is rare that we do not get enough copper. The risk is that we get too much.
If too much copper is consumed (even relatively small amounts), this can lead to stomach and intestinal complaints such as nausea, vomiting and diarrhea. Over time, an excess intake of copper damages the liver, kidneys, and nervous system; it can even be fatal.
A World Health Organization (WHO) expert committee recommends an intake of copper of 30 micrograms (µg) per kilogram of body weight per day, which equates to around 2 milligrams (mg) of copper per day for an average adult. According to the United States’ Food and Nutrition Board, an intake of between 1,5-3 mg per day is ideal.
We obtain our copper from food and water, as well as inhalation and contact with air, water and soil that contain copper. The foods that contain the most copper are some organ meats (such as beef liver), oysters, chocolate, potatoes and shiitake mushrooms, but it is also present in smaller quantities in turkey, crab, cashew nuts, sunflower seeds, tofu, millet, salmon and some fruits and vegetables.
In some cases, a little excess copper can be present in acidic foods or drinks that have been stored in copper containers. However, it is rare that too much copper is consumed via food.
The other main source of copper is the water we drink.
In its Guidelines for Drinking Water Quality, the World Health Organization established a safe limit for copper content of 2 mg per liter of water. However, this doesn’t take into account how much copper is present in standing water (water that has been sitting in contact with copper pipes for some time). The longer water is in contact with copper, the more copper it contains. This is why drinking water companies recommend letting the water flow out of the tap for a few minutes if the pipes have not been used for a long time (for example in the morning or after a holiday).
Most of the copper in our drinking water comes from corrosion of copper pipes and fittings, including brass faucets. Corrosion happens when metal and oxygen react with each other. Because there is oxygen in water, copper gradually corrodes. The water absorbs copper as it leaches from plumbing material. How much copper ends up in the water depends on the amount of minerals in the water (how hard or soft the water is), how long the water stays in the pipes, the water’s temperature, and the water’s acidity.
The type of corrosion at play in copper pipes is erosion corrosion. This happens when there is movement between the metal surface (copper pipe) and corrosive fluid (in this case, water). The surface of the metal gradually deteriorates due to the abrasion of fast-moving fluid [ref: https://theconstructor.org/structural-engg/steel/different-types-corrosion/35536/]. The speed of the water, the structure of the pipe installation, and the quality of the water all determine the degree of corrosion.
According to a study by the Netherlands’ National Institute for Public Health and the Environment (RIVM), corrosion of copper pipes poses environmental risks.
When copper enters the soil, it creates a toxic environment for microorganisms such as beneficial bacteria. It also inhibits the mineralization of nutrients such as phosphorus and nitrogen, something healthy soils depend on. Few plants can survive on copper-rich soil. Farm animals feeding on contaminated ground end up in poor health. When it comes to aquatic life, copper damages the kidneys, liver and nervous system of most freshwater creatures.
Water boards, responsible for purifying and treating wastewater, can only partially remove copper. As a result, this metal ends up in our drinking water sources. Then, drinking water companies have to purify water from drinking water sources to remove copper before sending it to our taps.
Geert Vinke, former information officer at the Association of Drinking Water Companies in the Netherlands (Vewin), noted the problem back in the 90’s. “Drinking water companies have increasingly become environmental companies that see drinking water as part of a cycle. As a drinking water producer, you don’t want to cause problems elsewhere in that cycle.”
According to Vinke, one solution is central water softening. This results in the water becoming softer, which decreases its metal-dissolving properties and in turn means less copper and lead residues coming out of the tap. However, this benefit is in part canceled by the growing number of household copper pipe installations and the copper that comes from agriculture (such as manure). Since copper does not break down, it builds up in the environment and surface water. In the Netherlands, copper and zinc concentrations regularly exceed water quality targets. They are therefore classed as priority substances for national policy.
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