When's the last time you flipped your water bottle over and checked the recycling number on the bottom? You may start making it a habit, when you learn a little more about what those numbers actually mean, according to the Natural Society. 

Each of the numbers located within the recycling symbol gives you a bit of information about the bottle or other container you are using. Here's a quick rundown of the most common numbers you will see on your food containers, according to the Natural Society:

1: This number is used on soda and water bottles. You may also see this number on salad dressing containers and peanut butter containers. Typically considered a safe plastic, it does tend to breed bacteria. 

2: Typically seen on milk jugs, juice bottles, shampoo bottles and yogurt containers, this type of plastic has a lower chance of leaching than most others and is considered one of the safer plastics to use. 

3: Most recycling companies don't take this type at your curbside. They sometimes contain phthalates and DEHA ,which are considered toxic. This number is most commonly seen on oil containers and some clear food containers. 

4: This plastic is one of the three safest and is typically found on frozen food bags, bread bags and food wraps. 

5: This is a safe plastic to use. You will find this number on ketchup bottles, syrup bottles and medicine bottles. 

6: Not only is this plastic difficult to recycle, it also contains chemicals that may be toxic, particularly if the plastic is heated up. You'll find this number on egg cartons, meat trays and plastic cups/plates. 

7: The only food item you will find this on is larger water jugs (3- and 5-gallon). This plastic is dangerous because it contains BPA, which has been linked to infertility. 

The Natural Society recommends that you avoid containers with the numbers 1, 3, 6 and 7 as they have the most potential for leaching unhealthy chemicals into the food. 

You can eliminate all risk by substituting your plastic containers for other options completely. How Stuff Works recommends glass, milk-based plastic or polyester.