Iron oxide plumbing tubes

Iron plumbing pipes are found in many old houses in the United States and in municipal water systems around the country. Iron pipes have the advantage of low cost and resistance. Iron pipe, as with anything else made of iron, is susceptible to oxidation damage, which can impair the performance of the pipe and ultimately plumbing and failure, which require replacing the pipes.

Signs of rusty pipes

Signs of a rusty iron pipe are red-brown stains on washbasins, toilets and washers; Chronic low water pressure; Water with a metallic or reddish taste; Chronic hot water shortage; Black water or smelly; And pipe leaks, especially in the joints. Oxidized pipes can be caused by water chemistry, electrolysis, water velocity and suspended solids. Galvanized iron pipe with a zinc coating decreases oxidation, but over time, the coating takes away and the tube begins to rust.

Chemical composition of water

Iron oxide oxidation can result if your water supply is very acidic, has high levels of dissolved oxygen, high levels of dissolved salts or high levels of corrosion-causing bacteria. To find out if your water is corrosive by a laboratory test called the ganglier saturation index. This test verifies the pH balance, electrical conductivity, dissolved solids and hardness and presents the results as a positive or negative number of the index. An index of zero indicates balanced water. A negative number indicates that the water is acidic and corrosive, while a positive number indicates that the water is alkaline and is likely to form carbonate and lime inside the iron tubes.


Electrolytic corrosion can severely affect iron pipes. Oxidation is an electrochemical process. Iron in water tends to enter the water as an electrically charged particle called an iron, or combine with another element already in the water. Iron ions flow through the water from negative to positive every time there is a gap in the electrical path through the pipe, creating a stain of mold. This natural tendency is increased when domestic wiring is grounded to the pipes, as required by many local building codes.

Water velocity

Water flowing through iron pipes at high speed can favor corrosion by bringing more dissolved oxygen into contact with the iron. If the water contains solids in suspension, they can wear down the walls of the tube. Too low a water velocity can cause stunting, stinging and bacterial growth. Water temperature also affects the rate of corrosion. Hot water is more corrosive than cold water. It accelerates the oxidation reaction in water as the temperature rises. Certain types of suspended organic matter encourage mold, while certain species of bacteria actually eat iron.