VAMWON Notes from the Field are a series of stories of the questions and sometimes the solutions I’ve encountered as a VAMWON volunteer or through my blog.
I received the following in a question/comment on my blog: “ I'm in Massachusetts and every year around December-January, our well water (which is normally really pure with great tests results) will start coming out reddish brown from the faucet. If I turn the water on and off a half dozen times, it gets even darker. I'm assuming that I get sediment build up and like clock work, it's time for this buildup to let go. Is that possible? If so, should I just plan on a good flush of the pipes once a year?”
Though my initial though was it was possible that the well was pulling mud since in Massachusetts in the winter groundwater are often at its lowest level. So I inquired about the depth of his well and when was it drilled. In addition, I asked if he monitored the water level.
He shot back with: “My well is a little over 300 ft. When this happens I turn on the outside faucets and let it run for about 3 -4 hours then it clears up. I hate to run it that long as we are conscience of our usage. We do not monitor the level. The well was drilled in 1994.”
That changes things. If the well did not run dry after running for 3-4 hours then it definitely was not going dry and this was truly a seasonal event. The question then became what changes in the winter. There are many possible causes of dirty water and I ususally recommend testing a well before calling a plumber, well driller, or water treatment company so that the problem can be properly diagnosed. It is usually cheaper to test your water than call a plumber and you need to understand what the real problem is to correct it. This time I had an idea of what might be wrong and a cheap and easy fix. So it is worth a try. What was different in the winter in Massachusetts (where most of my family lives) is road salt.
Road salt, sodium chloride, freezes at a lower temperature than water. When salt (or brine solution) is applied to the roads, the water won't freeze at temperatures above -6° Fahrenheit. Salt can also help existing ice melt faster. However, as the ice melts, the salt atoms dissolve into separate sodium and chloride ions. Chloride ions are oxidizing agents, and that combined with an old well where naturally occurring iron and manganese and any rust on the well casing is likely to be dislodged. This is true for wells and public supply water systems.
Iron and manganese are naturally occurring elements commonly found in groundwater in the northeast. At naturally occurring levels iron and manganese do not present a health hazard. However, often they build up over time in wells and on the well casing. I believe the elevated chloride ions are oxidizing the built up rust and minerals. High chloride ion levels from road salt entering groundwater supplies, combined with aging well casing and components could have released rust and brown drinking water from the well. So in this case since a likely solution is cheap and not really difficult to do, I would recommend that he fill the well with a 200 parts per million of chlorine solution and let it sit for 12-16 hours then flush the system completely. If this is done it might keep the problem at bay for a couple or three years.
In the commercial and public water supply sector it has been accepted for decades that the appropriate maintenance treatment for a well is to acid or chlorine treat to eliminate encrustation and buildup. Only in the past five to ten years so has this knowledge migrated to the private well sector. University extension departments now accept that as a well ages, the rate at which water may be pumped (commonly referred to as the well yield, flow or performance) tends to decrease. Now Penn State Extension states that “often, reduced well yield over time can be related to changes in the water well itself including:
- Incrustation from mineral deposits
- Bio-fouling by the growth of microorganisms especially iron bacteria. This is also likely to kill your pump.
- Physical plugging of "aquifer" (the saturated layer of sand, gravel, or rock through which water is transmitted) by sediment
- Sand pumping
- Well screen or casing corrosion
- Pump damage
They go on to state that the two most common methods to rehabilitate a water well are: chemicals to dissolve the encrusting materials from the well including acids and chlorine; and physically cleaning the well. Chemical treatment usually dissolves the encrustations and extends pump function. These days regularly treating a well with chlorine is the recommended strategy to extend the life of a well and equipment. See well maintenance tips from Penn State University Extension, University of Minnesota Extension, University of Arizona etc.
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