Sometimes the onset of discoloured water can be sudden and limited to a street or area. There may have been some activity in your area that may have changed the rate of flow or direction of flow in the water main. This could be the operation of a major valve or the flushing of a fire hydrant or a burst water main.
Water moves through the lines at a very slow rate, which allows sediment and mineral deposits to build up in the line, a change in the rate of flow can stir up these deposits causing a discolouration in your water.
To flush discoloured water from your lines, run at least two taps for several minutes, flush the toilet a couple of times, or turn on your garden irrigation system. It is recommended not to use hot water if the cold water is discoloured, as this will fill your hot water system with discoloured water.
If you are washing clothes at the time, it is best to stop the cycle with the machine full and wait until clean water is available to finish. Emptying the machine and allowing it to go into a spin cycle can cause permanent staining. Add a stain remover or dishwashing detergent to assist with removing stains that may be present.
If there has been no activity in your area and you are experiencing discoloured water in your home it could be from the internal plumbing system in your home. Older homes built in 1970 or earlier, may have galvanised iron pipes in their plumbing systems which may be starting to rust. This can cause drinking water to be brownish in colour and contain visible particles. The discoloured water would most noticeable first thing in the morning when there has been no water used overnight, or if the house has been left vacant for a while. It can also occur at seldom-used taps. The water should run clear after flushing the tap for a couple of minutes.
If this problem occurs in conjunction with a noticeable reduction in water pressure, the pipes may need to be replaced. To check if there is corroded galvanised pipe in your plumbing system, compare water samples from a tap near the water meter and from a tap further away in the house or in the backyard. If the water from the tap near the meter is of noticeably better quality than that from the tap further away, this indicates there is corroded galvanised iron pipe in the plumbing system.
Corrosion is accelerated in hot water systems. If the cold water is clear and the hot water is brownish in colour or contains noticeable particles your hot water tank could be corroded. Flushing the hot water system may help to clear out the sediment buildup in the bottom of the tank. Contact your local plumber for assistance.