Water with a rusty tint and metallic taste often indicates the presence of iron in your well water. Iron-containing water also stains laundry and dishes and causes buildup in pipes and tanks. Because of these effects, the Environmental Protection Agency sets the secondary maximum contaminant level for iron at 0.3 parts per million. Iron concentrations in natural waters usually remain below 10 ppm, but you may encounter higher concentrations. Choose a treatment method based on the amount and type of iron in your well water.
Fill a clear glass with tap water and observe the properties of the water. If the water is red as soon as it comes from the tap, it contains colloidal iron -- tiny particles suspended in the water. Red or black particles appearing in water after it has sat in the glass for a few minutes indicates dissolved iron.
Obtain an iron test kit from a certified environmental laboratory and follow the kit directions to collect samples of your well water. Send the samples to the laboratory to be tested. Have the samples tested for manganese, pH and hardness in addition to iron; you need these data to select the appropriate treatment system.
Remove iron with an oxidizing filter if the combined concentration of iron and manganese is less than 15 ppm. Install a manganese green-sand filter system if the water pH is between 6.2 and 6.8 or a birm filter system if the pH is between 7 and 8.5. Backwash either type of filter system according to the manufacturer's recommendation.
Use a two-step treatment system with oxidation and filtration for iron concentrations above 15 ppm or if your water contains colloidal iron. Chlorination followed by a sand filter is the accepted method for household systems, according to North Dakota State University. Alternatively, use an aeration system to oxidize the water. Operate and maintain the system according to the manufacturer's directions.
Replace the sand filter in an oxidation and filtration system with an activated carbon filter to remove excessive amounts of chlorine.
Consider using potassium permanganate for oxidation in place of chlorine if the pH of your water is above 7.5. Keep in mind, however, that the system must be carefully calibrated and monitored, as excess potassium permanganate in water is poisonous.
- U.S. EPA: Secondary Drinking Water Regulations: Guide for Nuisance Chemicals
- Cornell Cooperative Extension; Iron and Maganese in Household Drinking Water; Ann Lemley, et al.; January 1999
- Texas Cooperative Extension; Drinking Water Problems: Iron and Manganese; Mark McFarland, et al.
- North Dakota State University; Iron and Manganese Removal; Bruce Seelig, et al.; February 1992