Anti-Iron Water Treatments

Iron is a metal that is found often in both rural groundwater and in city water supplies that pass through older iron piping. When the water is drawn up it may be clear, but exposure to oxygen rusts the iron. It then leaves rusty brown stains on clothing, appliances and bathroom fixtures and produces an unpleasant taste in food. There are several proven ways of treating water to eliminate iron.

Air Injection

• This method removes iron from water without chemicals. It does so by spraying the water into a tank through an aspirator that adds air to the water. Because it uses a large storage tank, it can be an especially useful method for wells with low capacities. Four to five gallons per minute must be pumped through the aspirator for this process to be effective. The air added by the aspirator starts the oxidization process, causing the iron to turn into tiny particles of rust that can then be drawn through a filter bed. The filter must then be regularly cleaned to remove the iron extracted from the water.

Aeration and Settling

• This method is similar to air injection, in that the water is sprayed through a nozzle that mixes air into it and oxidizes the iron. Instead of filtering the iron out of the water, this system just sprays the water into a large tank. The iron particles, being heavier than water, then sink down to the bottom of the tank and clean water can be pulled from the top. As with air injection systems, the large tank capacity of a settling system lends itself to low capacity wells, which can be used to slowly fill a tank that can then be drawn down at the speed the user requires.

Water Softeners

• Water softeners use a reactive resin to replace molecules of iron (and other contaminants) with different, inert molecules (often sodium). The iron must be present in a clear form in the water, and the softener resin needs to be treated regularly with cleaners such as sodium hydrosulfite or phosphoric acid to keep it functioning properly. This is an appropriate method for concentrations of iron below 2 milligrams per liter.

Chlorination

• Chlorination can be used to remove iron in two ways. 200 milligram per liter chlorine bleach solution can be added to the water in the well to "shock" it, in a method similar to that used with swimming pools. If the chlorine is left in the water for 8 hours, it will kill many of the bacteria that can cause iron buildup. Chlorine can also be added to the water as an oxidizer that turns the iron into particulates of rust that are then filtered out. This works best with water with a pH of at least 7, exposed to the chlorine for at least five minutes. In both cases, the chlorine will need to be removed by an activated carbon filter before consumption of the water.

Manganese Greensand

• These filters draw the water through a bed of manganese oxide that oxidizes the iron in the water, allowing it to be drawn off in the same way as with an aspirator. These were once the most common type of iron filter, and are capable of removing iron in concentrations of up to 6 milligrams per litre. They can also remove small amounts of both manganese and hydrogen sulfide, but must be regularly regenerated with an application of potassium permanganate. This replenishes the oxygen atoms in the greensand that react with the iron in the water. Manganese greensand filters work best with water of pH 7 or above, a flow of 5 gallons per minute and regular regeneration.