“An easy way to clean a bottle without using a brush is by adding a couple of teaspoons of raw rice and a drop of dish soap, then filling it halfway with hot water,” says Katie Berry, a member of The Spruce's Cleaning Review Board and internationally recognized home cleaning expert. Once you’ve done this, put the lid on the bottle and give it a good shake. “The rice will scrub the bottle interior, and the soap will clean it.” Afterward, empty the bottle and rinse it thoroughly.