The discoloration you see typically comes from iron that accumulated in cast iron water mains and has been picked up by a large change in flow. This change can be caused by main break, repair or replacement, flushing, firefighting activities, or anything else that disrupts the normal flow through the water main.
Although iron appears unappetizing and may impart a metallic or slightly bitter taste, it offers no health threat. Extremely high levels of iron can induce nausea and vomiting, but that amount would not taste good and one would have a hard time drinking it.
Call the BWL Water Dispatcher at 517-702-6490. We want to know about every instance of this occurring, both to respond to your concerns and to help us understand all of the conditions that produce this iron pick-up. If you must have a drink of water, drawing some into a pitcher or tall glass and letting it stand will give the discoloration a chance to settle. Generally, if you wait for a short period (an hour or so), then flush your faucet for 10 minutes, the discoloration will disappear.
As always, call the BWL Water Dispatcher at 517-702-6490 to alert us when you see something unusual about your water. These are not normally hazardous but it’s helpful for us to know when and where they happen, when they do. The two most typical causes for what you describe are easily distinguished from one another. The first is air, which can enter the water mains either from a main break or main isolation, or from air due to the use of certain wells in the BWL system. The second is from deposits of calcium carbonate that have been laid down in the mains over time and then picked up due to large changes in flow. Collect cold water from you tap in a clear glass. If the water clears from the bottom up, it’s air. If the cloudiness is caused by calcium carbonate (product of the softening process) it will clear from the top down. Neither of these is hazardous, and both should disappear within hours. The exception might be during a dry, high-consumption summer, when many air-pumping wells must be used for extended periods. The air will take some time to work its way through the system once those wells are shut off again.
Some small amount of the dissolved iron from the water mains is carried into the bowl where it eventually meets oxygen at the surface and is oxidized. In the oxidized form iron can no longer stay dissolved in the water, and plates out on the porcelain surface. Iron oxide can stick to most any surface. It isn’t unusual for water that carries a very small amount of iron (0.1 parts per million) to, over a long period of time, cause bathtub surfaces and shower curtains to show an orange tint. The iron will not be visible in the water, but after it hits the air and the iron oxidizes, the iron oxide begins to accumulate on the surface. Most bathroom cleaners will remove this iron oxide.
Iron is the sixth most abundant element in the universe. It is usually found as an oxide ore; hematite. It can also be found in both surface water and in groundwater, but is more abundant in the latter.
Iron can occasionally be found in its elemental state, but reacts quickly with oxygen to produce oxides like magnetite (Fe3O4) and hematite (Fe2O3, otherwise known as “rust”). Iron can often be found dissolved in groundwater in its reduced form, where there is little oxygen present. In its oxidized form it becomes rust, and imparts a yellow, orange or brown color to water. Manganese is sometimes found associated with iron, but our local aquifer, the Saginaw, appears to have little or none.
Iron is a natural constituent of many soils and dissolves into water when oxygen is not around and groundwater is mildly acidic. Iron is naturally present in groundwater and because it is truly dissolved, is not normally visible to the eye. Some subsurface microbes use iron as an electron acceptor and then combine it with oxygen to form oxides. The BWL’s softening process removes almost all of the groundwater iron. What iron you see is almost always due to minor corrosion of cast iron water mains.
Please call our Water Distribution Department at 517-702-6490 to report water quality concerns. If you have technical or regulatory compliance questions, please call Angie Goodman, Water Quality Administrator, 517-702-7059.