How Microbiologically Safe Is Your Well Water?


Over 15 million US households drink well water, according to the CDC. These private wells are not covered by the United States Environmental Protection Agency (EPA) regulations that protect public drinking water systems. As a private well owner, this means that you are responsible for ensuring the quantity and quality of your own water supply.

Ground water has been used in California since the first inhabitants began using water that seeped from the springs. However, in some areas, the use of water is threatened by high rates of extraction and inadequate recharge, or by contamination of aquifers as a result of land use practices. Poor quality water is enough to make anyone want to change water providers. If you represent a commercial entity, you can find out how to switch your water supplier online. Although our country has one of the safest drinking water supplies in the world, sources can still become contaminated through:

  • naturally occurring chemicals and minerals
  • local land use practices
  • malfunctioning wastewater treatment systems
  • other sources

Top Causes of Outbreaks in Private Wells

If a private well was contaminated, it can impact not only the household it serves, but also nearby households using the same aquifer. Ground water is not 100% pure water and always contains some dissolved minerals, as it collects in the tiny pore spaces within sediments and in the fractures within bedrock. The presence of contaminants in drinking water can lead to health issues, including gastrointestinal illness, neurological disorders and reproductive problems.

The top 6 causes of outbreaks in individual (private) wells are:

  • Hepatitis A
  • Giardia
  • Campylobacter and E. coli (tie)
  • Shigella
  • Cryptosporidium and Salmonella (tie)
  • Arsenic, gasoline, nitrate, phenol and selenium (tie)

Private wells should be checked every year for mechanical problems, cleanliness, and the presence of coliform bacteria, nitrates and any other contaminants of concern. The well should be located so rainwater flows away from it, because rainwater can pick up harmful bacteria and chemicals on the land’s surface. If this water pools near your well, it can seep into it and could cause health problems.

Common Sources of Potential Ground Water Contamination

The following table shows the most common sources that lead to ground water contamination.

The Need for Water Testing

Because bacterial contamination cannot be detected by smell, sight or taste, the only way to know if a water supply contains bacteria is to have it tested. The EPA does not regulate wells and there is no requirement to have private wells, springs or other sources tested – it is up to the individual homeowner to do it. Those who depend on a private well should test their water source at least 4 times per year but if not possible, at least 1 time is mandatory. Private water supplies should generally be tested for bacterial safety as follows:

  • any time a component of the water system is opened for repair
  • at least once a year
  • when a laboratory test indicates high nitrate and human or livestock waste is suspected
  • when a new well is constructed
  • when an existing well is returned to service
  • whenever bacterial contamination is suspected, as might be indicated by continuing illness
  • whenever the well is inundated by flood waters or surface runoff

Testing for all individual pathogens is impractical and expensive. Bacterial safety of drinking water is monitored by testing for coliform bacteria. If tests reveal the presence of coliform bacteria, there is an indication that pathogenic bacteria, protozoa and viruses may also be present in the water. Some city/county health department laboratories as well as most commercial water testing laboratories provide bacterial testing for private well owners, for a fee.

You can contact the nearest laboratory and ask for a drinking water bacterial purity test kit that will allow you to collect a sample of your well water and send it to the laboratory for testing. The laboratory must receive the sample within 48 hours of collection, otherwise it will not test it.

Well Water Treatment Options

If testing confirms the presence of coliform bacteria in your water, you should use an alternative water supply or disinfect your water supply until the problem can be corrected. Whilst a water heater can be used to kill off bacteria that enters the home it is best to err on the side of caution. First American amongst other advisors warn that if the temperature of the water heater is too low, bacteria like legionella can fester inside the heater itself. All in all, it is probably better to treat the bacteria at the source. Treatment methods proven to be effective for removal or inactivation of some pathogens like enteric viruses, Giardia, Legionella or Cryptosporidium include:

  • disinfection and/or filtration
  • disinfection with UV light
  • disinfection with ozone
  • disinfection with chlorine

The easiest cure and overall least expensive is to install an Ultra Violet (UV) system. Properly matched to the water peak flow, the UV will provide years of protection with the only maintenance required being an annual bulb change. Energy requirement is less than most light bulbs and installation is quite simple. Call us at 760.734.5787 and get in touch with one of our water experts today!


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