Iron bacteria consume iron to survive and in the process metabolize the iron into a protective slime layer around the cells, making them very resistant to elimination. Iron bacteria do not cause health problems but do leave a reddish brown or yellow slime that can clog plumbing and foul water softeners and iron filters. You may notice this brown or rust colored stringy-appearing slime in your toilet tank when you remove the lid. In addition to causing plumbing and fixture problems iron bacteria clog well screens and reduce well yields. Iron bacteria can produce odors that may resemble fuel oil, cucumber, or sewage.
These odors may be noticeable only in the morning or after periods when the water has not been used. Iron bacteria can co-exist with various species of sulfur bacteria which can give off a rotten-egg odor. Treating Iron Bacteria by Shock Chlorination Even though chlorine is a powerful disinfectant, iron bacteria can build up a thick slime that keeps the disinfectant from penetrating beyond the surface cells. In addition, iron, manganese and hydrogen sulfide gas that are often present in well water can absorb much of the chlorine before it has a chance to reach the bacterial cells. Because chemical reactions are slowed at the cool temperatures common in wells, bacterial cells need a long exposure for chlorine or other disinfectants to be effective. Even if chlorine kills all the bacterial cells in the water, those in the groundwater can be drawn in by pumping or drift back into the well. Because of these factors, thoroughly treating an iron bacteria infestation requires more than simply dumping bleach into the well.
The following steps are recommended:
Approximately 8 quarts of 5.25% household chlorine bleach should be mixed with 100 gals. of water. The goal is to prepare an amount more than the amount of water standing in the well, and so the 100-gallon measure is a safe estimate if this is not known. You can mix this water in several clean trash containers. Pour or pump the solution into the well. Attach a hose to an outside hose bib or faucet and place the other end of the hose into the well. Open the faucet and circulate the water for at least one hour washing down the inside of the casing and the pump piping. Faucets in your house should be opened until you detect a chlorine smell, and then close them. Allow the chlorine solution to remain in the well and piping for at least 24 hours, before purging the system free of the chlorine. If you have a chlorine test kit, make sure there is at least 10 ppm of chlorine left in the well water after the 24 hours. If you detect a chlorine residual less than 10 ppm, repeat the entire shock chlorination process if possible. Run the chlorinated water outdoors on a field or ditch since it can have a negative effect on septic tanks. It may also kill grass and shrubs, and under no circumstances should be run into a pond or stream. Well owners may need to repeat this process more than once in order to rid the system entirely of the iron bacteria. Prevent Iron Bacteria Infestations When a new well is drilled, or when an existing well pump is repaired, soil containing bacteria can be introduced into the groundwater from pipes or pumps that were laid on the ground. Surface water used as drilling water may also infect the well with iron bacteria. An improperly constructed or maintained well can be contaminated by surface water leaking into the well. In some cases floods will force surface water into the well and cause contamination. Poorly maintained or defective septic systems, barn or cattle areas, and other sources of contamination may allow water containing bacteria to penetrate the well through open cracks in the bedrock. Although these sources may cause more serious water quality problems which could cause disease (such as e.coli bacteria, parasites and viruses) they could also be sources of iron bacteria in a well. Well Chlorinators In many cases the iron bacteria are not eliminated despite repeated attempts to sanitize the well and plumbing. At this point a permanent and on-going disinfection system may be employed. Chlorine is the most common disinfectant used in home water well systems, but hydrogen peroxide and ozone are also highly effective against iron bacteria. If the well is losing production due to iron bacteria slime and build-up a chlorine pellet feeder that dispenses chlorine pellets down the well may be the best solution. The chlorination, peroxide or ozone injection system is typically installed after the well but before the water enters the household piping in order to disinfect the water of iron bacteria. A large enough contact tank must be employed in order for the water to be thoroughly disinfected after injecting the disinfectant.