If you're in the habit of washing and reusing plastic water bottles, you may want to limit the practice.
Washing water bottles before you reuse them can help cut down on illness-causing bacteria. However, researchers caution that washing and reusing disposable water bottles over and over may accelerate the breakdown of the plastic, increasing your exposure to potentially harmful chemicals. Limit yourself to one or two reuses.
In addition to repeated exposure to water and soap, disposable plastic water bottles may be further degraded by exposure to sunlight. Store your bottled water in a cool, dark place. Reuse disposable plastic water bottles for no longer than a week or so, then recycle them.