Iron Bacteria

It was time for my semi-annual Alternative On-Site Sewage (AOSS) System service/ inspection as required by the manufacturer and under Virginia regulations. At the scheduled time my service company arrived and I followed them around to chat about how the system was holding up. Unfortunately, my Delta Whitewater system and drip field have had many problems over the years, and I prefer to take advantage of the inspection/ service to ask, listen and learn. Once more the “zoner” valve was leaking, but fortunately a new gasket solved the problem and this year I escaped replacing the zoner again. However, the scum level appeared to be quite thick. This was perplexing since 5 months earlier when I was away on vacation the septic company had supposedly pumped the tank and charged me for it.  I looked at the scum layer and took a couple of pictures- yeah, I know, gross. The field service technician went back to headquarters to try and determine what could have caused so much scum. The company determined that they must have mistakenly not pumped the tank and sent out the truck to pump my tank.

Looking at the pictures and thinking about my previous experience with my septic tanks- I had never previously had that level of scum even with several years between pump outs. This is a two person household and I am careful with grease, fats, oils and scraps.  So, I asked around and searched for other solutions. I received one from Sandra Gentry of Gentry Septic Tank Service and Secretary of Virginia Onsite Wastewater Recycling Association (VOWRA). Though Sandra did not know the answer off the top of her head she was able to tap into her network of contacts and find a possible cause for my problem.Sandra suggested that the cause might be iron bacteria. That bacteria reportedly just love all the excess oxygen in an ATU (the second tank in my AOSS that the system blows air into 24/7). According to Sandra the iron bacteria should look a bit like a brown Jell-O. I examined the pictures I took and thought, maybe.

Though I test my well water each year for all primary and secondary pollutants, iron bacteria is not part of that suite of tests and frankly I had not thought to test for iron bacteria. Generally, there are symptoms of iron bacteria.  Iron bacteria often produce unpleasant tastes and odors commonly reported as: "swampy," "oily or petroleum," "cucumber," "sewage," "rotten vegetation," or "musty." The taste or odor may be more noticeable after the water has not been used for some time and are not easily explained by other causes. Iron bacteria do not produce the "rotten egg" smell common to hydrogen sulfide, but do create an environment where sulfur bacteria can grow and produce hydrogen sulfide. There is often a discoloration of the water with the iron bacteria causing a slight yellow, orange, red or brown tint to the water. It is sometimes possible to see a rainbow colored, oil-like sheen on the water. Though the classic symptom of iron bacteria is a rust colored slime, but may be yellow, brown, or grey. I had noticed none of those symptoms and I drink my water without further treatment.

However, I had on occasion noticed a subtle bit of white filament on the bottom of pitchers of water and that could be a symptom.  So, I ordered an Iron Bacteria Test from National Testing Laboratories took a water sample following the instructions and overnighted the shipment to the laboratory who found “Iron Related Bacteria” present with an estimated population of  2,300 cfu/mL.  This level of iron bacteria is “top tier” and needs to be addressed. Iron bacteria once introduced into the well will not get better, but continue to get worse destroying your pump and ultimately fouling the well. Left unaddressed sooner or later I would no doubt experience some of the very unpleasant symptoms of iron bacteria. Although iron bacteria can make water unpleasant in taste or smell, there is no health risk associated with the bacteria. They are harmless, but annoying. 

Elevated levels of iron or manganese in groundwater are an ideal media for iron bacteria to grow. Iron bacteria are present in soils and surface water in this area of Virginia and in many parts of the country. Iron bacteria can be introduced into a well during drilling, repair, or service if  tools, equipment, or devices used during well drilling or pump servicing were not properly disinfected. It is believed that the bacteria must be introduced into the aquifer and cannot infect the water without human help. Some health departments in parts of the country that are also iron rich recommend  chlorinating the well once a year or anytime it has been opened or serviced as a method of prevention and control of the bacteria. Elimination of iron bacteria once a well is heavily infested can be extremely difficult. Normal treatment for a problem such as this would be to chlorine “shock,” but iron bacteria can be particularly persistent and chlorine treatment of the well may be only partly effective.

Physical removal is typically done as a first step in heavily infected wells where the functioning of the pump and well production have already been impacted by the bacterial slime buildup. The pumping equipment in the well must be removed and cleaned, which is usually a job for a well contractor or pump installer. The well casing is then scrubbed using (disinfected) brushes or other tools. Physical removal is usually followed by chemical treatment with chlorine (or less commonly acids). Chlorine is inexpensive and easy to use, but may have limited effectiveness and may require repeated treatments. Effective treatment requires sufficient chlorine strength and time in contact with the bacteria, and is often improved with agitation. Though typically a chlorine concentration of 200 parts per million for decontamination of a well, a higher concentration is recommended by the literature for iron bacteria. Recommended concentrations are between 500-1,000 parts per million. Be warned that too high a concentration can make the well to alkaline and reduce effectiveness. In addition high concentrations of chlorine may affect water conditioning equipment, appliances such as dishwashers, and septic systems. You may want to check with the manufacturer of the appliances before chlorinating.

Though it is relatively easy to bypass equipment, iron bacteria may remain in the units and reintroduce the iron bacteria into the plumbing system. The recommended strategy is to treat the well with a 500-1,000 parts per million chlorine and then dilute the remaining water in the well. This can be accomplished by allowing a significant amount of the water to runoff to a safe disposal location using hoses until the water runs clear, and allow the well to refill and dilute the concentration then introduce the water into the house water system to disinfect the household treatment units, appliances and piping with lower concentrations circulated through the water system. The Idaho Water Resources Research Institute recommends an initial treatment at 1,000 ppm including scrubbing and disinfecting the pump and an annual maintenance disinfection of 500 ppm leaving the pump in place. Constant chlorination (which should be followed by activated carbon filtration to remove the carcinogenic chlorine breakdown products)  is not typically necessary and falls into the category of over treatment. The less treatment the better.  

Pasteurization of the well is another technique that has been successfully used to control iron bacteria. Pasteurization involves a process of injecting steam or hot water into the well and maintaining a water temperature in the well of 60°C (140 degrees Fahrenheit) for 30 minutes. Pasteurization can be effective, however, the process may be expensive and all the well equipment needs to be pasteurized as well and holding temperature for thirty minutes can be difficult especially in deep wells. Chemical treatment with chlorine is the most commonly used iron bacteria treatment technique and the one I used. I coordinated the well treatment with pumping the septic tanks and then as recommended to me by Sandra to chlorinate the heck (she did use a slightly different word) out of all my septic tanks to kill the iron bacteria that is already there (as well as all the other bacteria) and then allowed the system to return to normal function naturally.

I hired a well driller for this job, to have him pull and clean the pump, chlorinate the well and water system and used pumping my septic tank to dispose of the high chlorine concentration water. However, if you want the instructions to calculate the amount of chlorine bleach to use and the steps to take to treat your well read the instructions from Minnesota (which includes instructions for water softeners and other water treatment systems), but use 4 times the chlorine they suggest for the initial well treatment since these are the instruction for the less persistent chloroform bacteria.  A couple of months after the job was done, confirmation testing confirmed the success of the project. In the future I plan to test my water regularly for iron bacteria and only chlorinate my well as necessary. My approach is to always perform the least amount of treatment necessary on my well and water.