According to the National Groundwater Association (NGWA) bacteria and nitrate are prevalent in the environment, so household well owners should make a habit of regularly testing their water. 

“We recommend that well owners test their water annually for bacteria and nitrate because of their widespread presence,” says Cliff Treyens, NGWA public awareness director. “Knowing whether or not you have a problem with bacteria or nitrate through valid laboratory testing is key to keeping your water safe.”

Most bacteria found in water don’t cause disease but disease-causing bacteria, called pathogens, can exist in well water, NGWA says. Nitrate is not unusual in rural areas because of its use in fertilizers and occasional link to animal or human waste.

Additional sources of nitrate:

•             Decomposing plant and animal materials

•             Sewage

•             Septic systems

•             Industrial effluent

•             Landfills

The biggest health concern from nitrate is “blue baby syndrome.” It is seen most often in infants, ages 0 to 3 months, exposed to nitrates from drinking water used in baby formula. The syndrome affects the ability of the baby’s blood to carry oxygen to body tissues.

Reverse osmosis works best on point-of-use systems like the kitchen sink, where water is used mostly for drinking and cooking. Ion exchange, along with a water softening system, can provide a whole-house solution for nitrate contamination.

Potential sources of bacteria:

•             Runoff from woodlands, pastures and feedlots

•             Septic tanks and sewage plants

•             Domestic and wild animals.

Potential pathways of bacteria into well water:

•             Reduced pressure or suction in water lines that draw soil water at the pipe joints

•             Faulty sanitary seals in a well system, i.e., faulty well cap, grout, pitless adapter.

Coliforms, or naturally occurring bacteria, may indicate the possibility of pathogens. The presence of fecal coliform or E. coli bacteria could mean water has been contaminated by human or animal waste harmful to human health. Pathogens can cause diarrhea, cramps, nausea and headaches. At most, they can be lethal.

If test results show the presence of bacteria in well water, a qualified water well system professional should determine the cause or source, perform needed maintenance and disinfect the well system.

NGWA is a nonprofit that supports responsible development, management and use of water resources. It’s comprised of groundwater professionals ranging from contractors to equipment manufacturers to scientists and engineers. For more information, visit

For more information on water well maintenance, visit