Blue/Green water (Copper Corrosion)
Blue or green water is caused by the corrosion of internal copper piping. Generally, the water discolouration is accompanied by a metallic taste. This is a complex problem that at elevated levels of copper can have health implications. it is caused by the release of copper from copper pipes into the water.
While low levels of copper are essential for good health, the National Health and Medical Research Council (NHMRC) have specified a health limit of 2 mg/L for copper levels in drinking water. Water with a copper level greater than this amount should not be consumed or used for food preparation.
Water with levels this high is usually seen as cloudy or blue/green with blue particles present. Sometimes, after boiling the water in a kettle or saucepan, the water or particles may change to black/brown and settle on the water surface.
Identifying the cause:
An effective method of observing the copper level in tap water, is to run the water first thing in the morning, into a clean white container (a bucket or ice-cream container). The tap should be allowed to run at full flow to fill the container with about 2-3 litres of water, with the container left to stand for a few seconds. If the water appears blue or if there are blue particles present in the container, the copper level may be near or above 2 mg/L.
If so, run the affected tap at full flow for about 30 seconds. The white container should then be used as before for a visual check. Water is usually acceptable to use when it is clear. If the initial flushing did not work, continue until the water becomes clear. You will probably only need to flush the taps first thing in the morning or if the water has not been used for some time. Practice will show you how long is necessary for your property.
Note: This procedure is a measure by observation only and does not actually measure of the copper levels in the water.
Copper pipe corrosion is a worldwide problem and the cause is not clear. Usually only one or two taps may be affected, however it is not uncommon for all taps in a property to experience varying levels of copper corrosion.