Iron belongs to VIIb group of Periodic table of the elements and it is in group of transition metals. Iron is common metal in Earth crust and represents fourth element according to presence in Earth. It occurs in compounds of oxides, chlorides, sulphates and sulphides. Iron salts (like chlorides) are very soluble in water, but iron (II) easy oxidizes in iron (III), which makes indissoluble hydroxide. This compound deposites, so low iron concentration expects in raw waters in surface source. Ablution of iron salts and industrial waste can be pollution source with iron.
Origin in water
Iron present in soil, but the content in underground waters is low because soluble of iron oxides, hydroxides and carbonates are very small. Maximal quantities of iron occur in very acid waters (pH<3), which are characteristic for zones of sulphides ores, so the iron content can go to 1 g/l. In contrast of oxidation environment, in reduction environment iron content in underground waters goes to tithe of mg/l. In presence of free oxygen Fe2+ is mutable and easy transform in Fe3+. In the most cases this processes are happening in presence of iron bacteria (Thiobacillus Ferrooxidans).
Iron is useful in construction of red blood cells. It is also part of haemoglobin and transfers oxygen in to the blood. Indications of iron lack are weariness, weakness, pale skin, cold hands and feet, insomnia, breakable hair and nails, qualm, constipation, and even impotency.
Iron, which is not used, amasses in interior organs and destroys them. This can bring to cirrhosis or diabetes.
Maximal allowable concentrations
According to recommendations of EU, limitary value for iron is 0, 2 mg/1 (exceptions for short overflow are not foresaw) (Directive 98/83/EC). According to our rules for drinking water (Sl. list SRJ 42/98), iron concentrations which can arouse objection of consumer is 0, 3 mg/1. The same values are for the water treatment for drink with iron salts (coagulation and flocculation).
Annotation: said limitary value is for the water at overall consumer; until on exit from plumbing, iron concentration must be appreciably lower, because of corrosion prevention