The Truth of Water - Answers

Joanne from Australia Writes:

We just bought a house thats about 50 years old.  The water has a faint brown colour.  I think the pipes may be rusty.  Is it a health hazard to drink and cook with this water.  I mean by giving us cancer etc

Hi Joanne, thanks for writing in.

If your water has a brownish or reddish colour to it, this could indeed be rust.  To find out for sure, put this water into a clear glass and let it sit for a few hours.  If the water clears and you see some sediment or a film at the bottom of your glass, this is oxidized iron.

This rust can come from several places.  It can come from older galvanized steel piping.  If you have municipal water, it is common to get some discoloured water when the water operations staff do routine flushing of the pipes.  This should go away very shortly.

If you have a well, the colour could be coming from an iron well casing, or from the water itself. It is very common for ground water to have dissolved iron in it, and as you pump it you add oxygen to the water, oxidizing the iron into insoluable form and causing the discolouration.

A small bit of oxidized iron is not bad for you.  Your body uses this naturally occurring mineral. The only concerns are aesthetic, as no one wants to cook with or drink coloured water.

Often with older piping or wells if the water has not been used for a siginificant period of time this can lead to leaching the iron. Try running all of your taps for 10 or 20 minutes each.

A sediment filter can also remove the rust, and these are available inexpesively at your local hardware store.

I hope I’ve answered your question to your satisfaction. If you have any more questions or require further clarification, do not hesitate to write in again.

Almost everybody at one time or another has experienced turning their tap on and getting a shot of red, rusty or yellowish water.  This is true for those who are both on municipal water and those on their own wells. But why is this, what is this and where does it come from?

Municipal Water

For those who are on municipal water services, you are fortunate to receive clean and drinkable water right to your taps.  So why does clean, drinkable water sometimes shoot red or yellowish water?

It has to do with the natural metals that are dissolved in water.  The most common of these is iron. Municipalities that use well sources for their water supplies tend to have higher iron concentrations than those that use surface waters.

Iron is dissolved in water until it is exposed to air, or another oxidant like chlorine. It then becomes oxidized and insoluble in water. You get tiny flakes of rust.  This is an aesthetic concern, not a health one, but as most of you know it can be annoying.

These little particles of rust settle out in the water main feeding water to your house.  When water is flowing through main at a normal speed, it achieves something called laminar flow.  This is when the water in the center of the pipe is traveling faster than the water around the sides of the pipe, due to friction.

The iron tends to settle out at the bottom of the pipes because of the laminar flow. If municipalities let it accumulate, soon there would be so much rust at the bottom of the pipes that the water would pick this rust up and all you would have is red water!  To combat this, municipalities institute flushing programs.  They open hydrants at various locations full on to induce what is called turbulent flow. When water is moving fast enough, it becomes so turbulent that the pipe friction doesn’t matter and all the water is in motion at the same speed. This picks up almost all the deposited iron and removes it from the pipes.

Sometimes though, you get a little bit of the rust in your service connection.  This is why you get a momentary shot of red or yellowish water.  It goes away after a minute or two of running your water.

Private Wells

Private wells can also have dissolved iron just like municipal wells can.  You tend to get iron when the well water is mixed with air during the pumping process, as well as when you turn your taps on. The latter will explain why you get rust stains in your sinks and tubs.  People who have older iron well casings also tend to experience high levels of iron.

A water softener will sometimes remove some iron. To remove all of the iron, it must all be first oxidized to insoluble form and then filtered away.  You can use an air injector and a 5 micron sediment filter. For more effective results, use an oxidizing chemical like chlorine or hydrogen peroxide.

The red or yellowish water from dissolved iron is a nuicance, but it is not a health concern and as we have seen it is easily remedied.