Inside CR Test Labs: Coffeemakers

During the testing for our February 2009 report on coffeemakers (on newsstands and online in January), our technicians began to wonder about the off flavors and odors they detected in the heated water that came out of seven coffeemakers the first few times they used them.

In their instruction manuals, manufacturers nearly always suggest that you run at least one cycle of water through a coffeemaker before you make the first pot of coffee with your new appliance. Is that one cycle sufficient to eliminate off flavors and odors? That question also prompted our technicians to spot-check the water from the seven coffeemakers for residual chemicals.

They collected samples from water run through the machines according to the manufacturers' instructions and had an outside lab analyze the water for semivolatile compounds, including six common plasticizers (phthalates) used in consumer products. (The lab followed EPA method 8270.)

While no federal agency has issued warnings regarding phthalates in coffeemakers, such compounds remain a subject of scrutiny by the U.S. Consumer Product Safety Commission and environmental groups for their use in children's and personal-care products, and air fresheners.

Two of the coffeemakers we tested store the water until you are ready to make coffee, and our testers noticed they had hard, clear plastic parts that looked like polycarbonate, so they spot-checked these machines for bisphenol A (BPA), a compound commonly found in polycarbonate plastic that studies have linked to cancer, diabetes, reproductive abnormalities, and other health risks. The technicians stored water in these two coffeemakers for nine days, heating and collecting the water on three separate days during this period, then tested each water sample for BPA

The tests detected low levels of two semivolatile compounds—benzyl butyl phthalate (BBP), a plasticizer, and benzyl alcohol, a solvent commonly used in inks, paints, and epoxy resins—in water heated in six of the seven coffeemakers models. They also found very low levels of BPA in two of those six coffeemakers.

Based on our experts' analysis, the levels of compounds detected would not be expected to pose a health risk. They also seem unrelated to the off flavors or odors. What our tests don't indicate, however, is what a coffeemaker might release over the years it's in use. Consumers Union, the nonprofit publisher of Consumer Reports, remains concerned about BPA and phthalates that might leach from plastics used in myriad everyday products involving food contact.

To minimize off odors and flavors, wash any product you cook, eat, or drink with before you use it. This includes following the instructions that came with your coffeemaker and running a water-only cycle through at least once before brewing.—Ed Perratore

Essential information: Your coffee machine might not be the only source of off tastes and odors in what you brew—it could be your water. Read our latest review of water filters. Consumer Reports has been testing coffeemakers for decades. The black-and-white photo above, circa 1958, shows one step in the process of determining the strength of the coffee from different models.