IRON REMOVAL FROM WELL WATER

Identification of water problems
Many people determine the quality of the water they consume by how it smells, tastes or looks. Although these are important criteria, they are primarily aesthetic properties of the water. A glass of water may not look, smell or taste good, but it could still be suitable to drink from a health standpoint.
The way water looks, smells and tastes can be used to help determine what type of treatment is necessary to improve the quality of the water. The following guidelines will help you determine if there are any problems with your water and what the most likely cause of those problems might be. All you need is a clear container to take a water sample and then use your senses of sight, smell and taste.
APPEARANCE
Water is clear when first drawn from the raw water tap then becomes yellow or reddish in appearance, but clears upon standing for 24 hours.Dissolved iron present.
Water is yellow or reddish when first drawn from the raw water tap but clears upon standing for 24 hours.Undissolved iron present.
Yellow or brownish cast to water even after softening and/or filtering and does not clear up after standing for 24 hours.Tannin (humic acid) in water. Comes from water passing through coal veins, peaty soils and decaying vegetation.
Black cast to water that clears upon standing for 24 hours.Dissolved manganese present.
Milky water.Excessive air in the water caused by the well pump sucking air (excessive drawdown) or a malfunctioning pressure tank. Also, can be caused by high amounts of bicarbonate precipitates resulting from an increase in pH.
Blackening, tarnishing, or pitting of metal sinks, utensils, pipes, etc.High amounts of salt (chlorides and sulfates) or hydrogen sulfide gas.
Green stains on sinks and other porcelain bathroom fixtures. Blue green cast to water.Acidic water (pH below 6.8) reacting with brass and copper pipes and fittings.
Suspended matter in water.Caused by riled up water in a surface supply or sand pumping from a well.
Soap curds and lime scum in wash basins and bathtubs. Whitish scale deposits in tea kettle and on the ends of plumbing fixtures (faucet, shower head, etc.).Hard Water caused by calcium and magnesium salts in the raw water supply.
Stained aluminum cookware.High dissolved mineral content and high alkalinity in the raw water.
SMELL
Chlorine smell.Normal chlorination of public or private well sources.
Fishy, musty or earthy smell.Generally harmless organic matter. Commonly associated with surface water supplies.
Rotten egg odor from the raw water tap or directly from the well.Dissolved hydrogen sulfide gas in the raw water.
Rotten egg odor only from the hot water tap.Sulfates present in the raw water reacting with the magnesium anode which causes hydrogen sulfide gas. Can be corrected by removing the anode or replacing it with an aluminum anode.
Detergent odor and water foams when drawn. Also septic odor.Leakage from a sewer system is entering the water supply.
TASTE
Salty flavor to the water that may have a laxative effect in some situations.High salt content (primarily sodium sulfate and magnesium sulfate).
Metallic taste.High concentration of manganese, or possibly other metals.
Correction of the water problem
When the cause of a water problem has been identified, then a method of treatment can be used to correct or minimize the problem. Before purchasing a treatment system, first have your water analyzed by a state certified laboratory to determine the quantity of foreign material in your water. The most common water tests are for:
Coliform Bacteria
Nitrates
pH
Total Dissolved Solids
Hardness
Iron and Manganese
After the water is analyzed, you can use the following chart to determine what treatment methods are needed to correct the problem. You may have identified more than one problem. If this is the case, you may need more than one type of treatment. Many reputable water treatment companies have equipment that will treat more than one problem.
Raw Water Problems and Commom Treatment Methods------------------------------------------------------------Raw Water Problem Common Treatment Method------------------------------------------------------------Bacterial contamination Treat using chlorination or other forms of disinfection (boiling, iodine, etc.) until the source of contamination is found and corrected or removed. Fine sand, clay Remove using mechanical (fine screen) or other sediments or sand filtration. Odor and taste other Corrected with activated carbon than ROTTEN EGG SMELL filters. Hydrogen Sulfide Gas Remove using chlorination followed by (ROTTEN EGG SMELL) sedimentation or use an oxidation filter (sometimes called an aeration filter) followed by an activated carbon filter to remove excess chlorine. Small amounts of Remove with a common water softener. dissolved iron and The water softener manufacturer should manganese. have a level of iron removal rating. Higher amounts of Remove using an oxidizing agent such as dissolved iron and potassium permanganate or chlorine manganese followed by a mechanical screen or use a green sand filter. Suspended iron and Remove using mechanical (fine screen) manganese particles or sand filtration. Hard water Treat using a water softener. Acid water Treat with a neutralizing filter (adds (pH less than 5.0) calcium carbonate) Alkaline water Treat by injecting a weak acid (acetic (pH greater than 9.0) acid or white vinegar) Tannin (humic acid) Remove using chlorination with a detention tank or a special anion exchange unit. Volatile organic1 Remove using an activated carbon compounds, certain filter. Other treatment options pesticides, trihalo- include reverse osmosis or distillation.methanes and radon Nitrates, heavy metals* Remove with reverse osmosis or by (lead, copper, etc.), distillation. Nitrates can be removed high total dissolved with an anion exchange unit.solids (TDS), sodium, sulfates.------------------------------------------------------------*These problems are not generally noticeable to human senses. Testing for these constituents should be performed by a trained professional familiar with the problems that can cause these forms of contamination.
Common water treatment methods
A brief description of the six most common types of household water treatment is found on the following chart. The list explains the main use for the treatment method and also, equally important, the major limitations of the method.
Common Home Water Treatment Methods------------------------------------------------------------------------Treatment Method Main Use Restrictions------------------------------------------------------------------------Water Reduces water hardness minerals Replaces calcium and Softening (calcium and magnesium) by magnesium with sodium replacing them with sodium. which can present a problem for people on Softened water requires less low sodium diets. A soap or detergent for washing kitchen faucet should be and cleaning. left unsoftened for drinking purposes. Reduces scale formation in Periodic backwashing and pipes, water heaters and on regeneration of the faucets. Improves sudsing resin bed using salt ability of soaps and detergents. brine is required.------------------------------------------------------------------------Oxidative Reduces iron and manganese Periodic backwashing Iron concentrations to levels where required. PeriodicFiltration they don't stain clothes or recharging with potassium plumbing fixtures. permanganate is required. Prevents odors caused by hydrogen sulfide Should be installed (rotten egg smell). upstream from a water softener.------------------------------------------------------------------------Activated Removes general taste and odor Generally does not Carbon problems including chlorine. remove nitrates, sulfates,Filtration bacteria or heavy metals. Usually installed at the Periodic replacement of point-of-use for drinking activated charcoal and cooking. (usually in canisters) is required forcontinuous operation.------------------------------------------------------------------------Reverse Reduces heavy metals, most Does not remove all Osmosis pesticides, and fluoride to organic chemicals such acceptable levels. as chloroform. Does not remove 100% of most Used primarily for drinking chemicals. and cooking. Uses large amounts of water for flushing.------------------------------------------------------------------------Distillation Removal of dissolved minerals, Produces bland tasting trace amounts of heavy metals water. and many organic chemicals. Requires significant Used primarily for drinking energy, therefore small and cooking. capacity units are used. ------------------------------------------------------------------------Chlorination Disinfection of biologically Not recommended as a contaminated water supplies, continuous practice for "shock" treatment of wells and the control of bacteria storage tanks. in private water wells. A new, bacteria free Aids in the removal of high source of water should be levels of iron and manganese. found. Additional treatment is required to remove residual chlorine and chlorinated organics.------------------------------------------------------------------------
Shock chlorination procedures
For shock chlorination, an initial chlorine concentration of 50 to 100 parts per million (ppm) with a contact time of at least 6 hours is recommended. To obtain a concentration of 100 ppm you need to know (or estimate) the diameter of your well and the depth of water in the well. Note: Do not use the total depth of the well. The depth of water is the distance from the water surface to the bottom of the well. Your well driller may have this information or you can determine it yourself by lowering a weighted string to the bottom of the well. Table 1 shows the amounts of chlorine bleach to add for an initial concentration of about 100 ppm. Table 1. Chlorine Bleach Additive Quantities------------------------------------------------- Well Diameter Depth of Water in Well (feet) (inches) less than 50 100 150 200------------------------------------------------- Quarts of Laundry Bleach 2 1/4 1/4 1/4 1/4 4 1/4 1/2 3/4 1 6 1/2 1 1.5 2 8 1 2 2 3 10 1.5 3 3 3 12 2 3 4 4-------------------------------------------------
Any type of laundry bleach containing 5.25% hypochlorite solution will work. Because bleach is corrosive to metals it should be diluted in the ratio of 12 parts of water to 1 part bleach prior to adding to the well water. These corrosive properties also mean that care should be taken in handling to avoid contact with skin and especially eyes. Rubber gloves and goggles are recommended when handling chlorine solutions. If you are exposed, flush repeatedly with clean water. This should be done immediately after exposure.
Follow the steps below to properly shock chlorinate your well:
Step 1. Determine the amount of bleach and dilution water to use (see Table 1). For example if you have a 4 inch diameter well with 40 feet of water, Table 1 recommends using 1/4 quart of bleach. To dilute, use 3 quarts of water (12 times 1/4 quart).
Step 2. Remove the cap from your well. There are many types of well caps. If you have questions or need instructions to remove the cap, contact your well driller.
Step 3. Pour the mixture of chlorine and water down the well. Try to coat the casing (sides of the well) as you pour. To get good distribution in the well, attach a hose to a nearby hydrant or faucet and put the discharge end of the hose in the well. Then start the pump to recirculate chlorinated water back into the well. The recirculating water should have a strong odor of chlorine if the chlorine demand has been met.
Step 4. Run water through the service lines in the house until you detect the odor of chlorine at each tap. Make sure you run the chlorinated water through every line in the system. You may also want to flush toilets. Note: If you have an activated carbon filter in the system, temporarily remove the cartridge or bypass the filter completely.
Step 5. Let the chlorinated water stand in the system for at least 6 hours, preferably 8 to 12 hours.
Step 6. Flush out the system beginning with the well. Use a hose connected to an outside hydrant and discharge the water to an appropriate waste system. Note: This large volume of chlorinated water should not be put into a septic system or onto delicate plants or lawns. After water from the well is free from chlorine odor, flush the rest of the piping system. Draining this volume of water into your septic system should be acceptable.
Depending on the age and condition of your well, you may want to shock chlorinate the well up to 10 times before abandoning the well. If you must use the present contaminated water supply until the new supply can be developed, be sure to follow a process of continuous chlorination.
Single-pipe Packer Jet Water Systems
If your well has a single-pipe packer jet water system you can disinfect it thoroughly only by removing the drop pipe from the well. Add the chlorine solution into the jet pump by disconnecting the tube at the air charging device and placing it in the chlorine solution (see Figure 1). The solution will be drawn through the pump, the jet fittings, the upper portion of the well, the drop pipe and the distribution system.
Because there is a foot valve at the bottom of the drop pipe, very little, if any, chlorine solution can enter the well below the packer leathers (see Figure 2). Therefore you must pull the drop pipe to disinfect the well thoroughly. With a packer jet water pump, chlorinate the water system before you remove the jet fitting from the well.
· 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 ofwater 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