This Best Practice Guide on the Control of Iron and Manganese in Water Supply is one of a series produced by the International Water Association’s Specialist Group on Metals and Related Substances in Drinking Water. Iron and manganese are often found in soft upland water sources associated with natural organic matter and are also commonly found in the groundwater abstracted from confined and unconfined aquifers. The presence of iron and manganese in water is one of the most frequent reasons for customers’ complaint due to aesthetic issues (yellow, brown and black or stains on laundry and plumbing fixtures). These two metals can be removed fairly readily by physico-chemical treatment. The municipal treatment systems deployed derive benefit from their larger scale, particularly in relation to control, but the processes used are less suitable for the numerous small supplies that are the most common water supplies throughout Europe, especially in rural areas. One important source of iron in drinking water is from old corroded cast-iron water mains, historically the material used most commonly in supply networks. Replacement and refurbishment is very expensive and the major challenge is how best to prioritize available expenditure. The purpose for this Best Practice Guide on the Control of Iron and Manganese in Water Supply is to give readers the broad view of a problem based on state-of-the-art compilation of the range of scientific, engineering, regulatory and operational issues concerned with the control of iron and manganese in drinking water. The Guide is of interest to water utility practitioners, health agencies and policy makers, as well as students on civil engineering and environmental engineering courses. Authors: Dr Adam Postawa, AGH University of Science and Technology, Faculty of Geology, Geophysics and Environment Protection, Krakow, Poland and Dr Colin R Hayes, University of Swansea, UK, Chair of IWA Specialist Group on Metals and Related Substances in Drinking Water.

Iron is a major constituent of the earth crust. However, under alkaline conditions commonly found in arid and semi-arid environments iron becomes unavailable to plants. When plants are affected by a shortage of iron their leaves become yellow (chlorotic), and both plant growth and crop yield are reduced. The roots of plants affected by iron deficiency may develop a series of responses directed to improve iron uptake, such as increased proton excretion and iron reduction capabilities or excretion of iron chela tors called siderophores. Iron deficiency affects major crops worldwide, including some of major economic importance such as fruit trees and others. Correction of iron deficiency is usually implemented through costly application of synthetic chelates. Since these correction methods are very expensive, the competitivity of farmers is often reduced and iron deficiency may become a limiting factor for the maintenance, introduction or expansion of some crops. In spite of the many years devoted to the study of iron deficiency, the knowledge of iron deficiency in soils and plants is still fragmentary in many aspects. We have only incomplete information on the processes at the molecular level that make some plant species and cultivars unable to take and utilize iron from the soil, whereas other plants grow satisfactorily under the same conditions.

The mission of the International Fertilizer Development Center is to increase food production through the improvement of fertilizers and fertilizer practices for the developing countries with special emphasis on tropical and subtropical agriculture. The principal aim is to ensure that fertilizer technology is not a limiting factor to food production in those regions. Although the full extent to which deficiency of micronutrients hampers food production is yet un known, there is ample evidence that problem areas exist and more will be identified as crop production is intensified and marginal lands are exploited. Therefore, it seems fully appropriate at this time that IFDC, as an international organization, take a leadership role in developing micronutrient fertilizer technology appropriate for the tropics and subtropics. The gravity of micronutrient deficiency as a limiting factor to crop pro duction varies from crop to crop and from soil to soil. The effects may range from slight yield reductions to complete crop failure. While the economic impact of omitting micronutrients in seriously affected areas (e.g., Zn in Brazilian Cerrado) is convincing, it is difficult to estimate the yearly loss in crop production due to unsuspected micronutrient deficiency. Active soil and crop testing programs in regions with advanced agricultural systems are aimed at recognizing micronutrients as a limiting plant nutrient in time to allow corrective measures and prevent yield loss. Successful micronutrient monitoring systems are generally limited to developed economies or to developing economies producing export cash crops.