Chlorinating My Well

The weekend before last I finally got around to chlorinating my well. There are so many things that regular chlorination will solve or prevent that you might want to consider it a regular part of home maintenance. I do it to knock back the iron bacteria and keep my water tasting good.

Iron bacteria, while not a health hazard, are an incredibly common nuisance in water wells, and once you have it you will always have it. Iron bacteria are a type of reducing bacteria that uses dissolved iron in the water as an energy source and leave slimy deposits of red iron hydrate as a by-product. Reducing bacteria can also thrive on sulfur and/or manganese. Elevated levels of iron, manganese and sulfate 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 other parts of the country. Iron bacteria can be introduced into a well during drilling or repair. There are tests that can look for these micro-biologicals.

I test my well water each year during the annual water clinic the Prince William Extension Office hosts and every few years for all primary and secondary pollutants under the safe drinking water act but, iron bacteria is not part of those suite of tests. The standard bacteria tests test for coliform and fecal bacteria and do not test for iron bacteria. However, about 15 years ago I tested my well water for iron/reducing bacteria and found a significant level. There had appeared a number of symptoms that suggested its presence, so I looked. National Testing Laboratories sells a mail in test for $150 plus shipping if you want to test your well. That is what I used.

Now, I just monitor the iron bacteria by checking my toilet tanks. The slime from iron bacteria builds up in toilet tanks and can be felt on the flapper. Also, the iron bacteria makes it look orangie in the tank. Interestingly enough I’ve noticed that he slime builds up at different rates in different bathrooms, I’ve not figured out why that is, maybe use. 

Iron bacteria once introduced into the well will not get better. Instead, it continues to get worse ultimately binding up your pump and fouling the well. Iron bacteria can grow on pump intakes and screens openings reducing the yield and efficiency of the well. In addition, the bacteria will make the water smell and taste vaguely unpleasant. Iron bacteria also causes a foam to form in the ATU tank of some kinds of alternative septic systems. A much earlier symptom is the slime on the toilet tank flipper. 

It is common practice to regularly treat public supply wells to prevent biofilm buildup from reducing bacteria and mineral encrustation. Preventive maintenance is to chemically treat and flush the production well.  However, this has not been the practice in private water well, though now several state health departments and Canadian Provinces are recommending the regular chlorination of private wells to push back the iron bacteria. While discussing his research in the Piedmont region of Virginia, Brad White a groundwater geologist from the Virginia Department of Environmental Quality Office of Ground Water Characterization happened to mention that in every well he put a camera down he had observed iron bacteria.

From Penn State Extension: “As a water well ages, the rate at which water may be pumped tends to decrease.” Penn State attributes this decrease in performance of a well to incrustations and biofouling (with reducing bacteria) of well screens and rock fractures or borehole, saying: “In severe cases, the obstruction to flowing water can render the well useless. Major forms of incrustations can occur from build-up of calcium and magnesium salts, iron and manganese compounds, or plugging caused by slime producing iron bacteria or other similar organisms (bio-fouling).”

Private well owners typically try to treat the symptoms rather than the cause of the problem. Elimination of iron bacteria once a well is heavily infested can be difficult. Iron bacteria cannot be eliminated by most common water filtration methods or water softeners. Iron bacteria will foul that equipment.  However, though it is difficult to eliminate, it is actually very easy to control – just oxidize the heck out of the well. This is accomplished by chlorine shocking of the well with adequate chlorine concentration and several hours of mixing accomplished by recirculation.  

Personally, I chlorinate my own well every few years or so to prevent the buildup of a biofilm in my well and plumbing system and maintain the aesthetic quality of my water. I drain and flush the hot water heater annually to protect it from biofilm and mineral buildup and keep the temperature above 145 degrees to prevent the growth of reducing bacteria.  If you have treatment equipment like a water softener, you might want to consider chlorinating your well annually and treating your media to prevent a bio mat from forming in the media tanks.

There are so many things that regular chlorination will solve or prevent that you might want to consider it a regular part of home maintenance. The first couple of times I chlorinated my well, a large amount of reddish brown mucus like gunk came out that after recirculating the well for three hours I ran the water off for three hours. Then upped the chlorine concentration and recirculated it again before I pulled the water into the house and sealed the well. 

These days when I chlorinate I only get reddish brown tinged water after a few hours of recirculating the chlorine water mixture.  At this point seen below, I seal up the well  and don't use any water. Once the well has sat for 12-14 hours with the chlorine mixture, I run the hoses to a non-sensitive area for at least an additional 14 hours till it runs clear and the chlorine level drops towards non-detect. Though it can take an additional  week to clear a well of every trace of chlorine under normal use. 

By the time the chlorine is fully mixed, the water turns brown

Even if you do not chlorinate your well regularly, you should chlorinate your well when:

• the well is new
• the well has been repaired
• the well has been flooded
• the well exposed to bacterial contamination in another manner, such as a crack in the well cap  

In addition, you should test your well at a minimum for coliform bacteria each year, usually in the spring (or the wet season), and if there is any change in the taste, color or odor of your drinking water. A confirmed positive test for coliform bacteria requires disinfection at the least. I did not chlorinate my well until after I reviewed the results of my recent well testing. The approach I would take to disinfect the well and plumbing systems is a little more involved (and inconvenient) than what I would do for iron bacteria alone. So, I waited to make sure I only needed to treat for iron bacteria.