SOLVING IRON PROBLEM IN WELL WATER

 Aeration followed by filtration
High levels of dissolved iron and manganese at combined concentrations up to 25 mg/l can be oxidized to a solid form by aeration (mixing with air). For domestic water processing, the "pressure-type aerator" often is used.
In this system, air is sucked in and mixed with the passing stream of water. This air-saturated water then enters the precipitator/aerator vessel where air separates from the water. From this point, the water flows through a filter where various filter media are used to screen out oxidized particles of iron, manganese and some carbonate or sulfate.
The most important maintenance step involved in operation is periodic backwashing of the filter. Manganese oxidation is slower than for iron and requires greater quantities of oxygen. Aeration is not recommended for water containing organic complexes of iron/manganese or iron/manganese bacteria that will clog the aspirator and filter.
 Chemical oxidation followed by filtration
High levels of dissolved or oxidized iron and manganese greater than 10 mg/l can be treated by chemical oxidation, using an oxidizing chemical such as chlorine, followed by a sand trap filter to remove the precipitated material. Iron or manganese also can be oxidized from the dissolved to solid form by adding potassium permanganate or hydrogen peroxide to untreated water. This treatment is particularly valuable when iron is combined with organic matter or when iron bacteria is present.
The oxidizing chemical is put into the water by a small feed pump that operates when the well pump operates. This may be done in the well, but typically is done just before the water enters a storage tank. A retention time of at least 20 minutes is required to allow oxidation to take place. The resulting solid particles then must be filtered. When large concentrations of iron are present, a flushing sand filter may be needed for the filtering process.
If organic-complexed or colloidal iron/manganese is present in untreated water, a longer contact time and higher concentrations of chemicals are necessary for oxidation to take place. Adding aluminum sulfate (alum) improves filtration by causing larger iron/manganese particles to form.
When chlorine is used as the oxidizing agent, excess chlorine remains in treated water. If the particle filter is made of calcite, sand, anthracite or aluminum silicate, a minimum quantity of chlorine should be used to avoid the unpleasant taste that results from excess chlorine. An activated carbon filter can be used to remove excess chlorine and small quantities of solid iron/manganese particles.
Any filtration material requires frequent and regular backwashing or replacement to eliminate the solid iron/manganese particles. Some units have an automatic backwash cycle to handle this task.
The ideal pH range for chlorine bleach to oxidize iron is 6.5 to 7.5. Chlorination is not the method of choice for high manganese levels since a pH greater than 9.5 is required for complete oxidation. Potassium permanganate will effectively oxidize manganese at pH values above 7.5 and is more effective than chlorine oxidation of organic iron if that is a problem.
Potassium permanganate is poisonous and a skin irritant. There must be no excess potassium permanganate in treated water and the concentrated chemical must be stored in its original container away from children and animals. Careful calibration, maintenance and monitoring are required when potassium permanganate is used as an oxidizing agent.
Table I. Treatment of iron and manganese in drinking water
Indication Cause Treatment
Water clear when drawn but red-brown or black particles appear as water stands; red-brown or black stains on fixtures or laundry Dissolved iron or manganese  Phosphate compounds (< 3 mg/l iron)
 Water softener (<5 mg/l combined concentrations of iron and manganese)
 Oxidizing filter (manganese greensand or zeolite) (<15 mg/l combined concentrations of iron and manganese)
 Aeration (pressure) (<25mg/l combined concentrations of iron and manganese)
 Chemical oxidation with potassium permanganate or chlorine; followed with filtration (>10 mg/l combined concentrations of iron and manganese)
Water contains red-brown particles when drawn; particles settle out as water stands Iron particles from corrosion of pipes and equipment Raise pH with neutralizing filter
Water contains red-brown or black particles when drawn; particles settle out as water stands Oxidized iron/manganese due to exposure of water to air prior to tap Particle filter (if quantity of oxidized material is high, use larger filter than inline; e.g., sand filter)
Red-brown or black slime appears in toilet tanks or from clogs in faucets Iron or manganese bacteria Kill bacteria masses by shock treatment with chlorine or potassium permanganate, then filter; bacteria may originate in well, so it may require continuous feed of chlorine or potassium permanganate, then filter
Reddish or black color that remains longer than 24 hours Colloidal iron/manganese; organically complexed iron/manganese Chemical oxidation with chlorine or potassium permanganate; followed with filtration
Adapted from "Iron and Manganese in Household Water," Water Treatment Notes. Fact Sheet 6, Cornell Cooperative Extension. (1989).
Estimate the water volume contained in the well casing using Table I and the "YOUR WELL" column of the following worksheet.
Table I. Volume of water contained per foot of well depth.
Well casing diameter (inches) Water volume per foot of
water depth (gallons)1
4 0.65
6 1.47
8 2.61
10 4.08
12 5.88
18 13.22
24 23.50
30 36.72
36 52.87
1Volume of water calculated as the volume of a cylinder multiplied by 7.48 gallons/cubic foot.
Step 1. Determine the depth of water in the well: The company that constructed the well should be able to provide you with the well depth and water level. For example, let's say that you have a 50 feet deep well, and the water level is at 40 feet. The well contains 10 feet of water (50-40=10 feet). You can view this information in Figures 1, 2, and 3.
Step 2. Determine the volume of water in the well. You measured the inside diameter of the well and it was 30 inches. Find the gallons per foot of depth for a 30-inch well in Table I. For our example we would multiply the depth of the water in the well (10 feet) by 36.7 gallons of water per foot of water depth (from Table I) to get 367 gallons of well water (10 x 36.7 = 367 gallons of water in the well).
For large diameter wells or cisterns, contact the Division of Drinking Water and Environmental Sanitation at the Nebraska Department of Health for information on how to disinfect your system.
Step 3. Estimate the volume of water in the distribution system. Total up the water storage in the system, including the water heater, pressure tank, etc., and add 50 gallons for the pipeline. If you have a 30-gallon hot water heater and a 30-gallon pressure tank, you need to add 110 gallons for the distribution system.
Step 4. Determine the water contained in the entire system. Add the water volume in the well to the water contained in the distribution system to get 477 gallons (367 gallons in the well plus 110 gallons in the distribution system).
Step 5. Determine the amount of chlorine product required for a 200 ppm solution. Table II lists the product amounts needed to create a 200 ppm chlorine solution using typically available sources. If you decide to purchase laundry bleach, you will need 3 pints of bleach per 100 gallons of water in the well and distribution system. For our example, you would need to purchase 14 pints or 1.75 gallons of liquid laundry bleach. You would determine this by using the worksheet at the end of this article (477 gallons divided by 100, multiplied by 3 pints per 100 gallons, and divided by 8 pints per gallon is equal to 1.75 gallons).
Table II. Amount of chemical required to create a chlorine concentration of about 200 ppm.
Chemical name Amount per 100 gallons of water a
Liquid Laundry Bleach (5.25% NaOCl) 3 pints
Commercial Strength Bleach (12-17% NaOCl) 1 pint
Chlorinated Lime (25% CaOCl2) 11 ounces
Dairy Sanitizer (30% CaOCl2) 9 ounces
High-test calcium hypochlorite b (65-75% Ca(OCl)2) 4 ounces
aWell water containing iron, hydrogen sulfide, or organic substances may require more chemical to create a 200 ppm solution. Chlorine combines readily with these materials, making some of the chlorine ineffective as a disinfectant.
bHigh-test hypochlorite is available as a powder and as a tablet.
Step 6: Introduce the chlorine material into the well and distribution system. The best way to introduce chlorine material into the well is to dissolve the chlorine in a 5-gallon bucket of fresh water. Be sure the bucket is plastic and has been thoroughly washed. Then pour the chlorine solution into the well. Try to splash the solution on the sidewalls of the well casing as much as possible. Attach a hose to the water hydrant or faucet nearest the well and run water through the hydrant and back into the well (Figure 1). TStep 7: Let the chlorine disinfect the system. The most difficult step is to refrain from using water from the well so that the chlorine can disinfect the system. The system should remain idle for at least 2-3 hours, preferably overnight.
Step 8: Flush the system to remove the chlorine. After the water system chlorination has been completed, the entire system must be emptied of chlorine and thoroughly flushed with fresh water by running water out of each faucet or hydrant until the chlorine odor dissipates. Distribute the waste water on gravel roads or other areas without plants or aquatic life, which it might harm.
his will thoroughly mix the chlorine solution and well water.
Do not allow more than 50 gallons of chlorinated water to enter the septic system. If possible, attach a hose to outlets inside the house and distribute the water to a nongrass area away from the house. The chlorine will eventually evaporate into the atmosphere.
Step 9: Retest the water supply for bacterial contamination. The final step is to retest the water to ensure that the water source is bacteria free. Take a water sample 1-2 weeks after shock chlorinating the well, using the same procedures as before. Though most shock chlorination treatments are successful, do not drink the water until the laboratory results confirm that no bacteria are present. Retest the well every month for 2-3 months to be sure contamination is not reoccurring. If test results are negative, an annual water analysis program can be reinstated.
If the water supply continues to develop bacterial contamination problems after being shock chlorinated, continuous chlorination may be an option. Other options include repairing the well, or constructing a new well. It may be necessary to abandon the water source. Procedures for properly abandoning a well are explained in NebFact NF92-81, Plugging Abandoned Wells, available from your Cooperative Extension Office. You may want to contact a licensed water well contractor to perform these duties.
Chlorine Solution Calculation Worksheet
Calculate volume of water in well: Example: Your well:
1. Depth of casing: (See Figure 1) 50 feet __________feet
2. Depth to water: (See Figure 1) 40 feet __________feet
3. Total depth of water: (#1 - #2) 10 feet __________feet
4. Diameter of well: (Measure inside diameter) 30 inches __________inches
5. Volume of water per foot: (Table I, column 2) 36.7 gallons __________gallons
6. Total volume of water in casing: (#3 x #5) 367 gallons __________gallons
7. Volume of water in the system: 110 gallons __________gallons
8. Total volume of water:(#6 + #7) 477 gallons __________gallons
Calculate Amount of Chlorine Product for a 200 ppm Solution:
Chlorine product used: Liquid Laundry Bleach
9. Product needed per 100 gallons:
(Table II - circle the correct units) 3 (ounces/pints) __________(ounces/pints)
10. Total product needed:
(#8 x #9- circle the correct units) 14 (ounces/pints) __________(ounces/pints)
 If you use chlorine as the oxidizing agent, it is important to note that any excess chlorine will stay in the water. While chlorine is an effective disinfecting agent, unpleasant taste results from too much chlorine. Using an activated carbon filter is an effective way to remove excess chlorine and improve taste.
The pH of the water supply should be considered when choosing an oxidizing agent. If the pH of the water is less than 6.5, a neutralizing treatment is needed before chemical oxidation. Chlorine bleach is the most effective for oxidizing iron if the pH level is 6.5 to 7.5. Consequently, chlorination is not recommended for treatment of high levels of manganese because a pH level of 9.5 or greater is required for complete manganese oxidation. Potassium permanganate can oxidize manganese at pH levels of 7.5 or higher and is also an effective method of oxidizing organic iron.
However, caution must be exercised with potassium permanganate because it is both a poison and a skin irritant. Furthermore, it is very important that no excess potassium permanganate be present in the water supply. In addition, caution must be exercised when storing the concentrated potassium permanganate to ensure that it is kept where children and animals cannot access it. If potassium permanganate is used, careful calibration, maintenance, and monitoring of your water treatment equipment