Iron & Rust – The Stainers

Iron and Manganese

The telltale rust and black colored stains on sinks, toilets and showers, strong metallic taste and impossible laundry are clear signs that you have iron or manganese in your household’s water. Iron and manganese sometimes occur in water together and are sometimes accompanied by their very unwelcome friend, the rotten egg of the water world, hydrogen sulfide gas.

These culprits take on different forms and must be properly identified in order to choose the proper system for effective removal.


Iron in water typically takes on, commonly, three basic forms: ferrous iron, ferric iron and iron bacteria.

Ferrous Iron

Water that is clear when drawn but changes to a yellow or rusty color upon standing is known as ferrous or clear water iron. This iron has not yet been exposed to oxygen and therefore has not “rusted” or oxidized. This iron is totally dissolved in water. This clear iron can easily pass through standard home store sediment filters, thwarting the best efforts of homeowners, then later change to a staining color on the surface of sinks, toilets or showers where air oxidizes it.

No amount of sediment filters or even carbon filters can stop this type of iron. The clear iron simply passes right through the filter. After time, the water remaining in the filter does itself oxidize, clogging the filter, dramatically reducing the water flow rate, forcing the homeowner to continuously replace the filter inserts.

The secret to removing this type of iron is to get it to oxidize completely so it can be filtered effectively before it reaches the house.

Ferric Iron

Ferric iron is sometimes known as red water iron because of its rusty red appearance when drawn. It is actually clear water iron, which has been oxidized, usually from dissolved oxygen or other factors in the water. This type of iron is not dissolved in the water but rather is suspended in solution

Ferric iron can also be formed from ferrous iron simply by letting it stand for a while. This sometimes can be witnessed in toilet bowls. Homeowners are sometimes surprised to find that upon returning from vacation, the water in their toilets has turned color. This somewhat unpleasant example shows a transformation from ferrous to ferric iron due the addition of oxygen from the air.

The same transformation can be witnessed at sinks or bathtubs with drippy faucets. Clear water drips from the faucets, but after remaining a while on the surface of the sink or tub the water turns red or yellow indicating the presence of iron. Once again, ferrous iron has changed to ferric iron by the addition of oxygen from the air.

Even though particles of ferric iron are suspended in the water, there is still a big problem when trying to remove them with simple filtration. The iron particles will rapidly clog filters causing low flow rates and making frequent filter changes necessary. Additionally, ferric iron is almost always accompanied by ferrous iron, which will simply slip through the filter causing staining when it is finally exposed to oxygen from the air.

The secret to removing ferric iron is to use a large capacity, automatically backwashing filter.

Iron Bacteria

Iron Bacteria are actually living organisms, which feed on iron in water, iron pipes and fittings. They pose no health risk but can be very damaging to the plumbing system. These bacteria form a reddish-brown slime, which may clog pipes and fixtures. Occasionally this slime breaks loose causing spurts of extremely discolored water. Iron bacteria can be identified by reddish-brown or sometimes yellow, gelatinous formations on the surface of the water in toilet flush tanks or by slimy clumps of iron oozing form pipe leaks or corrosion. They can cause bad tastes and odors in the water supply.

Iron bacteria can not be treated by most common water filtration methods and can cause fouling in water treatment equipment. In extreme cases it can actually clog and destroy well pumps.

To treat this problem you must first kill the bacteria by chlorination or some other oxidizing-disinfecting method and then filter it out of the water.The well and all the piping must first be treated with heavy amounts of chlorine for an extended period of time, using a process known as “shock chlorination.”


Manganese is very similar to iron in its properties. In fact, they both often occur together with manganese composing a small part of the combination. Manganese can occur in a clear water state, latter turning to a colored water state. It can come from the well already oxidized due to dissolved oxygen in the water. There are also manganese bacteria which are similar to iron bacteria. . Manganese staining does often appear to be darker than iron staining (sometimes black)

The distinction between iron and manganese is usually not that important because most methods which successfully treat iron will also treat manganese. However, when a larger amount of manganese is present, modifications and additions to iron removal equipment may become necessary.