The phrase "to wash the bottles" means to clean the bottles by removing dirt, stains, or any other impurities using water and soap or cleaning agents. Full definition
Some studies indicate that chemicals in plastic bottles may leak when bottles are exposed to heat, so for this reason many mothers choose to hand wash bottles. (newkidscenter.com)
It is also important to note that participants did not drink hot beverages from the bottles and they didn't wash their bottles in a dishwasher, as many people do. (treehugger.com)
Get them in a pack of three, and you won't have to wash your bottles after every feeding. (mommyedition.com)