You Should Regularly Chlorinate Your Well

 It is common practice to “clean” public supply wells on a regular basis. This is often because of an observed decrease or loss of chlorine residual in treated wells which can allow contaminant entry into the well system. This is often caused by sediment or biofilm build-up within the well. Preventive maintenance is to chemically treat and flush the production well.  This need to regularly treat a well to prevent biofilm buildup and mineral encrustation has been well known and practiced for decades in small systems. However, this has not been the practice in private water well. That is beginning to change.

The last time I heard Brad White a groundwater geologist from the Virginia Department of Environmental Quality Office of Ground Water Characterization give a talk on the work DEQ was doing in Fauquier County, he 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 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).”

The Provincial Government of Alberta (Canada) says indescribing iron bacteria: “This slime will coat the inside of the well casing, water piping and equipment, creating problems such as reduced well yield, restricted water flow and red staining of plumbing fixtures and laundry. However, all iron- staining problems are not necessarily caused by iron bacteria. The iron naturally present in the water can also cause significant problems.” There are all sorts of odd problems that are caused by iron bacteria. Over time many wells develop these problems. These harmless bacteria can foul a well, damage pumps, stain plumbing fixtures, clog pipes, faucets, showerheads, and produce unpleasant tastes and odors in drinking water. Yet, water is very rarely tested for iron bacteria since very few certified laboratories conduct the test. 

Yet, 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.  

Thus, routine maintenance of a private water well should include regular chlorination to control biofouling of the well and maintain water quality. Personally, I chlorinate my own well on even number years 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 140 degrees.  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. 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 for 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.