Red rust may bring about health problems when you ingest more than a certain level. Iron is one of essential elements for human nutrition as our body requires 7 to 48 ml/L of iron a day. Iron is unlikely to be ejected from our body and has middle to high levels of toxicity. A large excess of iron intake may result in iron poisoning, such as hemorrhagic necrosis of gastric mucosa and crust formation. Iron can cause serious health problems to children. Some researches show that excessive intake of iron will cause small children emesis or diarrhea. Although lethal amount of iron is 200 to 250 mg/L, it could be fatal when children ingest more than 3 mg/L. It is also dangerous to pregnant women as iron may affect babies through their mothers. Iron content in water increases as corrosion damage is caused by red rust {FeO(OH) } in pipes.
Black rust (magnetite) protects inner surface of pipe from red rust and is a very hard crystallized material. Once red rust is reduced to black rust, it will provide with a protective coating on inner surface of water pipes.