Iron is a metal found naturally in water. It ranks fourth among the most abundant elements on earth, while in earth’s crust, it ranks second (Dordrecht, 1993). It is found in large quantities in rocks and soil systems around the world. It is a vital mineral nutrient, which plays role in the maintenance of energy metabolism. It is an important element in haemoglobin, myoglobin as well as in several types of enzymes. Low levels of iron in the body may cause iron deficiency, anaemia, fatigue and increased susceptibility to different infections (Green et al., 1968). Water bodies receive iron either through geogenic sources or via dumping of domestic waste and industrial effluents (Khatri and Tyagi 2015). The sources of iron in surface water are mainly pollution from iron and steel industries, mining and metal corrosion (Jusoh et al., 2005). Apart from surface water, iron is also present in groundwater. The major reason behind the presence of iron in groundwater is due to leaching from iron-bearing rocks and minerals (Tekerlekopoulou et al., 2013 ). The concentration of iron in surface and groundwater varies from 3 to 4 mg/L to 15 mg/L (Ellis et al., 2000). Its concentration in the groundwater of West Bengal, India was in the range of 2–10 mg/L. Concentrations of iron up to 6 mg/L have been reported in the Ganga river near the Fazalpur industrial area in Moradabad district of Uttar Pradesh, India (Kumar et al., 2017). The groundwater in Assam, the eastern state of India is highly contaminated with elevated levels of iron. However, the permissible limit for drinking water is 0.3 mg/L.
The presence of iron in groundwater is generally magnetite, sulphide (pyrite), carbonates (siderite), silicates (pyroxenes, olivine etc), under anaerobic conditions in the presence of reducing agents like organic matter and hydrogen sulphide (Saroj kumar Sharma, 2001).
Iron usually exists in natural water in reduced soluble divalent ferrous FE (II) and oxidised trivalent ferric FE (III) forms. In well-water, iron concentration underneath 0.3 mg/L were portrayed as unnoticeable, while levels of 0.3– 3 mg/L were discovered satisfactory.
Iron is a basic supplement for good wellbeing. It is a major component of haemoglobin, which is utilized to transport oxygen and carbon dioxide into the blood. Iron lack can increase lead absorption and toxicity; anybody with elevated blood lead levels should be tested for iron deficiency.
The intake of large concentration of iron can harm veins, cause bloody vomit’s/stool, and affects the liver and kidneys, and may even result in death. Apart from these health-related problems, many other issues of higher iron concentration in water have been reported. The iron imparts an odour, metallic taste and red colour to the water at elevated concentrations (Das et al., 2007). It also causes stains and streaks on laundry and plumbing fixtures.
The higher concentrations of iron may also act as a substrate for certain bacteria. The surfaces of pipes are the most suitable habitat for such bacteria. These bacteria increase to such high population that they start clogging pipes and reduce the flow rate of water in the pipeline. It becomes very difficult to remove such bacterial colonies once they get established in the pipeline. Moreover, if the pipeline is made up of iron, punctures and leakages are some of the common problems reported (Michalakos et al., 1997 and Colvin et al., 2017). When these bacteria die, bad odour and unpleasant taste are produced in the water.