Congratulations! You have your own private water supply. The water tastes great, and you have no monthly water utility bills to pay. You also have no one watching out to make sure that your water supply stays safe and sanitary, so that job is up to you. Managing your water supply is not difficult, but you need to be aware that there are times of the year and specific conditions that can contribute to contamination of the water well.
What can go wrong? Well, spring can arrive! With Spring in the Northern Rockies comes snow melt and rising rivers and streams. During the spring of the year, it is not uncommon for drinking water wells to become contaminated, because as rivers rise and fall, so does the groundwater. It is during this time that contaminants can be carried into the well. We strongly recommend that private water wells be tested just after spring run-off. Some other common problems we see include the following:
Improperly seated well cap or no well cap gasket
Broken conduit for pump wiring
No backflow protection on hose bibs
Improperly installed underground irrigation systems
Improper well construction
If you own your own drinking water well or spring infiltration system
If you notice changes in color, odor, or taste
If your water supply is near surface water
If your well is new or has never been tested
If the plumbing has been repaired or replaced
If the well head has been flooded
A household member is pregnant or nursing.
A household member has an unexplained illness.
You hear a neighbor’s water is contaminated.
You notice a change in water taste, color, odor, or clarity.
You replace or repair any part of your well system.
Your well has been flooded.
A basic water test checks the water sample for the presence of total coliform bacteria. Total coliform bacteria are common in the environment, but should not be found in water supplies or sources. For this reason they are used as indicator organisms. Fecal coliforms are a type of coliform bacteria found only in the intestines of warm-blooded animals. They can not reproduce or survive long outside of this environment. If a water sample is found to contain E. coli or fecal coliform bacteria, the water has either been in direct contact with raw sewage or has been in contact with something else that has been in direct contact with raw sewage. In either case, the presence of total coliform with or without fecal coliform in the water sample is considered "contaminated."
Typically, wells contaminated with low levels of total coliform bacteria may not taste bad or look different. In fact, if you have been drinking water from a contaminated well for a long period of time, you may not have any health symptoms. Visitors, young children, the elderly, pregnant women or folks with health problems may become ill from drinking the water. Symptoms usually include stomach ache and/or diarrhea.
Wells contaminated with fecal coliform bacteria, including E. coli may cause more severe stomach cramping, diarrhea and sometimes vomiting. If your water is contaminated, you can boil it for three minutes and let it cool before drinking it. Boiling will kill the bacteria. Store the boiled and cooled water in the refrigerator.
The process of killing the bacteria in your well is called "disinfection." For wells with high numbers of bacteria, more than one disinfection procedure may be required. Disinfection is typically done by removing the well cap and pouring a solution of household bleach and water down the well casing. Then the well cap is replaced and water is run through all the water piping in the home. Please see the Well Disinfection Sheet in Word or PDF form.
The only way to know your well water is safe is to have a sample of the water tested. The Missoula City-County Health Department water lab is certified to perform water tests. For information about our lab costs, see the Water Lab Fees link.
The Montana State Environmental Lab is set up to run many tests:
it can do chemical and metal screening, as well as biological and hardness
testing for water. Missoula City-County Health Department carries
of supply of water sample bottles from the state lab for your convenience.
Missoula City-County Health Department carries of supply of water sample bottles from the state lab for your convenience.