Iron in water

Pure water (H2O) does not have a taste. Most minerals including iron, will be absorbed by water. Large amounts of iron in drinking water can give it an unpleasant metallic taste. Iron is an essential element in human nutrition, and the health effects of iron in drinking water may include warding off fatigue and anemia.

There are two main forms of iron in water: ferrous iron and ferric iron. Ferrous iron dissolves in water, and it will not precipitate as a solid unless it is oxidized. The oxidized form of iron is ferric iron, which precipitates as a yellow, brown or red solid. These solid particles containing ferric iron tend to become suspended in water, giving it colour. Iron will leave red or orange rust stains in the sink, toilet and bathtub or shower. It can build up in your dishwasher and discolour ceramic dishes.

The iron sediments may contain trace impurities or harbour bacteria that can be harmful. Iron bacteria are naturally occurring organisms that can dissolve iron and some other minerals. These bacteria also form a brown slime that can build up in water pipes. Iron bacteria are most commonly problematic in wells, where water has not been chlorinated Left untreated, iron overload can lead to hemochromatosis, a severe disease that can damage the body’s organs. Early symptoms include fatigue, weight loss, and joint pain, but if hemochromatosis is not treated, it can lead to heart disease, liver problems and diabetes. A blood test can identify iron overload.

Both the SANS-251 2015 and the WHO recommend the following maximum levels of Iron in water :

Aesthetic ≤ 0.3mg/l
Chronic health ≤ 2mg/l

The iron content will determine the system needed to remove the iron from the water. Low levels (<2mg/l) can be remove with an inline FRP tank filled with DMI-65. The higher the content, the more complex and expensive the system will be. The water will have to oxidised to become ferric and can the removed with DMI-65. With very high levels, the water first needs to be softened and the PH must be adjusted to between 6.5 and 7.8 for the DMI-65 to be effective. It may also be necessary to dose the water at intervals with either sodium hypochlorite or hydrogen peroxide. The advantage of sodium hypochlorite is that it will also kills unwanted bacteria in the system These filters absorb iron and manganese from the water by converting them to an oxidized form and causing them to precipitate in the filter. These filters must be periodically backwashed to remove the deposited iron.

DMI6501 DMI6502