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Keyword: water contamination
photo of a capped residential wellKevin Koepenick, Manager, Ground Water Management Section
Baltimore County Department of Environmental Protection & Sustainability

As the primary agency responsible for permitting domestic wells and septic systems for Baltimore County, my staff and I receive frequent questions from county residents about the safety of their well water.  Specifically, they are interested in knowing how often their wells should be tested, what parameters should be tested, and who can do the testing.

I recommended that all private drinking water wells be regularly tested for bacteria.  The US EPA recommends testing for bacteria annually, but it is probably most important to test for bacteria immediately following any plumbing work (adding a bathroom, replacing a well pump, etc.) or if you notice your wellhead is damaged or was flooded, or if your well water gets cloudy after it rains.  Nitrate levels should also be monitored (but less frequently) to ensure that they are below the 10 ppm standard for drinking water, and pH is important to watch to assess if your water is corrosive.  Depending on your specific tastes /preferences, it is also recommended that you test for iron, manganese, chlorides, and hardness.  If you notice a gasoline or oily smell in your well water or suspect leakage from a nearby underground fuel storage tank, you should probably have your water tested for volatile organic compounds (VOCs).

In certain areas of the county you may also want to test for radium. Testing has confirmed that roughly 10-15% of the wells tested in areas underlain by Baltimore, Setters, and Slaughterhouse Gneiss formations have levels of radium above the US EPA drinking water standards.  The good news is that radium is easily removed by a standard water softener (a common water treatment device). 

As a private water supply, water quality testing is the responsibility of the homeowner.  There are a number of local private laboratories who provide these services.  For more details about water quality testing, wells and available labs, go to our website:

If you are interested in understanding more about radium, be sure and read the educational booklet entitled ‘Radionuclides and Your Well Water: A Homeowners Guide.”  You can also call our office at 410-887-2762 or send us an email at with any questions you might have.


Revised April 6, 2016