Harmful bacteria may be lurking in your single-serve coffee machine

Illness-causing bacteria may be hiding in your beloved single-serve coffee machine. (Keurig Green Mountain)

There's some bad news for coffee lovers brewing their morning joe with a single serve coffee maker.

According to a swab test conducted by KDKA-TV in Pittsburgh, over 4 million colonies of  harmful bacteria and mold was founding lurking in the water tank, coffee pod compartment, spout and tray on more than half of the 28 machines tested.

The station says it tested eight machines in Pittsburgh and another 20 in Chicago and Dallas and found strains of bacteria like E.coli, staphylococcus, streptococcus and pseudomonas aeruginosa.

“I thought you would find something, but not something that could make us sick,” coffee machine owner Stephanie Brink told KDKA.

According to the National Coffee Association, about 27 percent of consumers own single-serve brewers, such as Keurig or Nespresso.  But many people forget to clean their machines on a regular basis.

"Coffee makers are certainly a moist environment where mold and bacteria are known to grow in high numbers.  Our bodies can deal with them, but at some point they'll grow to levels high enough to cause sickness," Kelly Reynolds, a microbiology specialist at the University of Arizona told Consumer Affairs.

Keurig told KDKA that if a machine has not been used for several days, it is important to run “several cleansing brews to remove any internal standing water.”

Here are some other steps to prevent mold or bacteria from collecting in your coffee machine:

--Clean your machine regularly

--Run vinegar through it to help sanitize surfaces

--Use filtered water rather than water straight from your tap

--Change the water after each use

--Leave the lid off to allow the machine to air out

--Wipe the machine down daily