According to a 2010 study by the American Chemistry Council—which, it should be noted, represents some plastic bag manufacturers—many reusable bags contain coliform bacteria, a category that includes E. coli. Also important: 97 percent of the 84 people interviewed for the study had never (yes, ever!) washed their bags. So, if you’re transporting raw meat, seafood, and vegetables in your reusable shopping bags and have never washed them before, you run the risk of inadvertently cross-contaminating your groceries. Luckily, the solution is easy: just start washing your reusable shopping bags, according to the instructions below. Then, check to make sure you’re following the dos and don’ts of reusable bag storage. What You’ll Need:

Laundry detergentDisinfecting wipes or spraysCleaning cloths or paper towels

How to wash cotton reusable bags:

  1. The goods news is that most reusable cotton and canvas shopping bags are machine-washable, just check the care label to make sure. Use the hottest water setting possible, along with detergent.
  2. If you can, toss the bags in the dryer. Note: this may shrink some cotton bags slightly. Alternatively, line-dry the bag in an area with good ventilation to prevent the growth of mold and mildew.

How to wash nylon reusable bags:

  1. Hand wash the bag in warm, soapy water, making sure to get into the corners and crevices. You can also machine-wash the bag, but be sure to use the gentle cycle.
  2. Line-dry the bag in an area with proper ventilation to prevent the growth of mold.

How to wash recycled plastic bags (polypropylene bags):

  1. You probably have a stash of these exceptionally sturdy bags from Trader Joe’s and the like. Wash them by hand using warm, soapy water, and then line dry them completely before storing them away. You can also dry them with a clean towel to speed up the process.
  2. Alternatively, wipe down the bags with disinfecting wipes and allow them to dry. You may want to turn the bag inside-out to get into the corners and remove any crumbs or grime.

The dos and don’ts of storing reusable shopping bags

Don’t store the bags in the trunk of your car. This dark, damp storage spot may encourage bacteria growth.Do designate one specific bag for carrying raw meat. This will help prevent cross-contamination. Then, wash that bag after every use.Don’t store away bags that are damp. Make sure they’re completely dry first.Do a sniff test. Musty-smelling bags are a sign they should be cleaned.Don’t store other items, like gym clothes or sports gear, in bags used for groceries.